In 45yrs of reloading, I have never split necks on cases. Not on cheap commercial brass or any of the high grade brass either. I have only started annealing recently so that isn't what has helped me avoid split necks.
Based on my experience, I'd say split necks were more a consequence of overworking necks than anything else. I use bushing dies for (almost) all of my reloading and move the necks and shoulders no more than is absolutely necessary. The new craze of using mandrels requires a reloader to resize more than minimally, and then to upsize again. It may not be much but it does require more work to the neck then just using a proper size bushing.
Just my 2 cents, and it's probably worth less.
I go along with more of what you are saying. I started annealing over 20yrs ago. Only once, it stop my neck from splitting. I was shooting a belted mag. I was shooting a 308 NM, and using 300WM cases, which I had to FL resize the cases first. I had problem with neck splitting, and case separation at the bases. I change from FL to neck sizing and using a 300WM neck sizing die to achieve the sizing. It only sized about 3/4 of the neck. It chamber just fine. It stopped the case separation at the same time. Only losted cases after that to primer pockets.
Sinces then I have changed to annealing everytime.
I have argued about using a mandrel as your final step to size the necks. I do feel that it's is working the brass a lot.
I do cut my necks for even thickness to start with, with new brass. In days gone by I have seen necks out several thousans on one side or the other. I also noted at the time that my groups closed up some.
I also feet that cutting neck corrects the uneveness of the brass. So bushing sizing the necks to correct tension should be enough. Here there are reloader say no.
Now the fun part is I got a new rifle with a tighten neck area. So I will try it both ways to see if I get any difference in accuracy from one way or the other.
So far I had to cut a few cases for the smith to test the rifle here awhile back. I was able to size the necks to correct tension of .002".
I also have to watch for springback too. So I have some work to do to see what the outcome is going to be. I purchased an additional bushing to size the neck down a little smaller to use a mandreal to bring it back to proper tension. Biggest problem is my reloading gear is on Montana presently and I am on Mexico-North of over a month yet. I am going to try do some detail note on what the outcome is. I am 75 and still on a learning curve.
I use Peterson, Lapua, mostly now, but have use about any other brass I could get my hands onto. Some cases are not built for some of the rifle I shoot in better brass.