For versions of Windows before 10, I'd agree with this 100%. Windows 10 (or maybe 8-8.1?) pulled in a lot of functionality from Process Explorer and is much improved.

For developers Process Explorer (and ProcMon and a few other utils) is likely an improvement, but frankly if you're doing Windows development you should already have learned about them and probably some of Nir Sofer's tools as well (nirsoft.net). For 90% of people (even developers) you probably don't need what Process Explorer provides.

Side note, in Process Explorer if you turn on the lower pane (View menu or Ctrl-L) you can view all handles that a process has open, including file handles. That can be useful for identifying unrecognized processes.