lol for good measure i went back and examined these stats only to realize that the "evidence" that you presented that the rule change is the far and away the biggest reason for increased perimeter play is even more trash than i initially thought
your claim is that the league went from five big men, low post players being the the top 10 PPG in 99-00, to two in 00-01, and that we've never even remotely seen a change like this before. so there were three big guys who dropped off the list between those years: Malone, KG and Timmy
first, lets not kid ourselves into thinking KG was a true low post player, he was about as perimeter oriented of a big man as there was in the league. his "low post" buckets was mostly putbacks. he clearly favored using his perimeter skills and shooting long fadeaways. but for the sake of argument, we will consider KG as a low post scorer
at 9 and 10 on the list of top 10 ppg in 99-00 was KG and Duncan. the next four guys (11-14: Finley, Kobe, Marbury, Ray) were all within 1.1 ppg of being ahead of both KG and Timmy. it's not like there was some massive margin to overcome here.
also karl malone was 37 years old. yep, im sure age had nothing to do with his scoring drop
(cue a highly funny and original joke from ambchang about emojis to avoid addressing how trash his point is)
lets also consider what happened the next year. in 01-02, timmy and karl ended up right back on the top 10 (oddly enough, Karl being back on there despite another drop in scoring average), and if not for missing 30 games for injury, webber would have qualified to be in that list too, bumping it back up to 4 of the top 10 ppg scorers being bigs. based off your conclusion, i figured even more perimeter players would have ended up on the list, or at the very least, the list standing pat. it didnt. same thing for 02-03.
well how about we rewind in time a bit now? in 98-99, there were 4, arguably 5 low post oriented scorers in the top 10. 97-98, same thing, 4, arguably 5. then 96-97? hm, it drops to 3, with just Malone, Olajuwon and Ewing, but shaq missed some games so lets add him and the number is 4; a drop regardless. then 95-96 8 of them top 10 were post oriented, and that's generally how it was prior to that. so it appears the big adjustment from bigs to wings began not in 00-01, but in 96-97 (where it dropped from 8 of the top 10 ppg scorers being low post big men, to 4, which is a bigger drop than 5 down to 2, only to go back up to 4 the next couple years), where we saw Iverson enter the league, and then some jumps in scoring from Glen Rice (5ppg increase), Spreewell (5ppg increase), Kendall Gill (nearly 8ppg increase), and Payton (2.5 ppg increase), along with quite a few other perimeter players having noticeable jumps in scoring but didn't quite crack the top 10, while Robinson and Barkley began to age out. and the league steadily evolved from there.
and what was the main reason for so many jumps in perimeter scoring in 96-97? i guess we could chalk it up to the fact that teams were taking more advantage of the shortened 3pt line. or maybe its simply a matter of perimeter scoring being proven to be more effective than a slow paced, dump-it-down offense, resulting in more skilled perimeter players entering the league and developing, while big men were aging out and not being replaced due to less skilled big men in the pipeline.