This is interesting, but it seems it's more useful for WordPress sites with the specific WPDB logic they have.
It'd be more interesting if, instead, they could intercept PDO queries and add profiling to those, for example.
Still, free code is free code. I don't want to look down upon it, just that the utility for my case is limited.
The wpdb logic is an addon and only triggers if wpdb is found. Phptop might still be useful in the general case to quickly and cheaply find CPU hotspots.
Nowadays it would be necessary to also show the various Curl/API calls because they're so omnipresent and impactfull on PHP sites (as wait time and not CPU time)... But AFAIK it's pretty hard to intercept them in a generic way.