This, pre-SSDs, used to be a much, much bigger deal. Now it's not as big a deal, but if you've been using Macs for 20 years surely you've felt the difference between opening a window of an already-open app vs opening an app from scratch.
I personally love that I can have all the apps I want permanently open on my Mac, and never have to experience the delay of anything launching. A new window just pops up instantly when I wanna interact with an app. It's great.