It's not that Pakistan doesn't produce good batsmen, it clearly does and produces very good batsmen in fact. But the best batsman in the Pakistani team is often not close to being the best batsman in the world and that's because they almost always fail against the best side of their generation.
Take Javed Miandad for example. He was Pakistan's best batsman in the 80s and he did score lots of runs against most teams. But against the best side of the 80s which was the West Indies, he averaged merely 38, which itself was boosted in the fag end of the 80s after the fearsome four retired from the Windies pace attack. Before that, he was averaging close to 30 against the West Indies in the 80s.
Similarly, Australia were by far the best team in the 2000s decade and Younis averaged 31 and MoYo averaged 34 against Australia home and away during that decade.
You compare this to their Indian counterparts:
Gavaskar averaged 45 against the West Indies during the 80s.
Tendulkar averaged 54, Dravid averaged 45 and Laxman averaged 61 against Australia in the 2000s.
Miandad, Younis and MoYo were no doubt prolific run scorers against most other teams, but they were always weak against the best side of their generation, and if I have to point one distinct difference between the Indian and the Pakistani batsmen, it's that the Indian batsmen almost always perform against the best while their Pakistani counterparts fall short when faced against the best. Anyone would love to have a striker who scores 25 goals in their team, but you'd rather have a striker or even an attacking midfielder who scores 15-20 goals every season and brings his best performance against the best teams rather than a striker who scores 25 goals against other teams but goes missing against the Barcelonas and Real Madrids or City and Liverpool.
Babar is the best Pakistani batsman of his generation and India were the best side of the 2010s decade followed by Australia. He cannot face India in Tests but he didn't have a great average against Australia in the last decade (31). Tbf to him, he does have a good record against New Zealand averaging 45, which could be considered the best team of this decade so far in 2020s.
This is a good post and I agree that performance against the best sides matters when it comes to defining a legacy of a batsman - and I also feel this is one of the reasons Pakistani batsmen of 200s don't often get more credit (Inzi/Younis in particular, and also MoYo). It's not that they were always worse than Indian batsmen in non-Asian conditions; if Indians were exceptionally good against Australia, we've always been better than Indians against England. But the issue with placing too much importance on performance against one side is that the sample size of games shrinks and you can get skewed results. I'm going to take a look at two players: Sachin and Inzi.
Let's take a look at Sachin as he is a good example from India due to having played the most games against Australia when compared to the others in the Fab 5. He has a fantastic average of 55.00 against Australia with 11 centuries (includes 2 double-centuries) in 39 games! These are indeed incredible numbers. I opened up each of the 11 innings he scored a century in vs Australia (they all came in 11 different test matches). Guess how many of these 11 test matches Glen McGrath played in? Only one: the 3rd test (Chennai, 2001), which is remembered for the 15 wicket demolition job from Harbajhan Singh leading India to victory. All in all, McGrath played 9 test matches against Sachin, and Sachin scored 1 hundred.
Inzimam averages 31.40 against Australia (compared to his 49.6 overall) with only 1 century in 14 tests. Of the 14 tests, Glen McGrath played 13 of them (Inzimam's hundred came in one of those games he played in). So both Inzi and Sachin have a total of one hundred against Glen McGrath.
Now one might protest against the criteria of only playing against Glen McGrath, but that's because Glen McGrath was the standout bowler during Australia's reign and the chief reason for Australia's invincibility and why they won so many test series (the other being Warne). There are many examples of how Australia were unable to win test series once McGrath was out of the side due to injury
even when Warne was still there (see Ashes 2005, and many of India's famous victories against Australia). He was also specially good against Asian batsmen (though to be fair to him, almost all of the great batsmen of his time struggled against him, including Lara and Sachin). I'm not a statistician but I'd love to see the batting averages of the Fab 5 when Glen McGrath bowled against them. Mind you, some of Sachin's 11 100s came when McGrath was not playing cricket, but I'm just illustrating a point that a lot of the 100s (including the big ones from Laxman/Dravid) came against an OZ attack without McGrath - which skews their averages. This is
not to take anything away from the Indian batsmen playing well against Australia - after all they can only play against what's in front of them. But what fault is it of Inzimam that McGrath happened to be available for 13 of Inzi's 14 tests - and it makes you wonder how much better he would have fared had he more games against them without McGrath.
So that's one of the reasons it can be tough to only look at games against one team - because the sample size gets smaller. There are plenty of other criteria: average, match-winning innings, series-winning innings, innings when trailing, memorable innings, etc.