Let's talk overreaching instead of overtraining. Overreaching - not necessary to push it to that level for 99% of recreational lifters because their goals do not require it. Therefore, a very misguided fear and an overused term.
In the "bro sense", as overtraining is presented on forums 99% of the time, it goes like this:
Dude, 15 sets for chest is overtraining.
Is it overtraining? Probably not. Does this mean "bros" should still do it? Probably not.
Training volume and intensity has to be based on a lifter's current goals, progress history, etc. There are things advanced bodybuilders and powerlifters do that would be considered overtraining by most. Just because it's not overtraining for an advanced lifter doesn't mean it's a tool that is required for the other 99% of the lifting pool.
Most newbs do way too much extra work that isn't needed. Overtraining? No. Wasted time and energy? Yes.