Question About Leveling Up Stats + Weapon Peram

So for the most part I am wondering why a lot of builds stop at 40 str/40 dex/40 int/etc. Is this because it loses it's ability towards either powering you up or your weapons based on the peram bonus? Or is this just a nice point to stop at and start focusing on other stats.

Mainly I am wondering because I am using the Black Knight Greataxe and on the wiki it says that at 40 str and 25 dex (+5) it does 613 dmg. But since the peram bonus for str is B while for Dex it is E, wouldn't it just be better to dump points into str?

I would greatly appreciate it if someone could explain to me how this works.

After putting 40 in a stat you suffer from diminishing returns. While each point before 40 can add anywhere from 3-7 AR,each point after 40 will only add 1 at most, some may add 0. Its just not worth putting levels into it after 40 as its already stopped scaling effectively.

Okay, that answers everything. Thank you very much for the info.