The problem is that improvement can't continue forever, even with doping.
Who, exactly, would be sprinting 9.58 in still conditions?
Gay, Gatlin, Powell, Blake, Mullings, Montgomery, Johnson, Greene were all using, and none of them could touch 9.58
Who then? Nobody now, or in the foreseeable future.
That's the problem. So guys are going 9.9 this year to win...who would care if they were going 9.7, if there's a 9.58 out there? The never-ending quest for sensational new records would end at some point.
That point is now, with 9.58, 19.19, 43.18, 10.49, 21.34, 47.60, etc.
This reset is as good as any. In a few years those marks will be distant history and won't be used as current yardsticks. For instance, are any W400 performances actually compared to 47.60 these days? No. Ditto all the other marks.
It's time to clean things up and let those marks fade into history, to make a 9.8 sensational, and rare, again.