While I'm not sure if that is the case in every instance (some older TN panels may or may not feel "snappier" than some of the more modern IPS panels), it could be due, in part, to the differences in how each panel technology refreshes.
See RTINGS "WHAT IS" descriptions on this page:
https://www.rtings.com/monitor/learn/ips-vs-va-vs-tn
And as I've said previously, a TN and IPS monitor could have identical average GtG performance, but the distribution that makes up that average could differ; a TN might have faster transitions between the more obvious and frequently displayed shades, whereas the IPS may have faster transitions between the less obvious and infrequently displayed shades (or visa-versa, or even a mix).