I have rolled quite a few critical fails on skill checks - and I am OK with it. I do not view it as unrealistic. Take lockpicking, for example. It’s an easy lock and I’ve done this a hundred times in my sleep so a DC 5 lock with my +5 bonus should be automatic - except that the stupid lock pick snapped off in my hand because it had a flaw - or - I didn’t notice that a tiny stone had gotten jammed in the lock before I tried - or - whatever. These things happen in real life, even on “automatic gimmes”. How many times on a real life intelligence check have you had something that you definitely know, but you just can’t pull up its name in your head? Geez, I can even see it and I had a whole college section on it, but I can’t pull it up in the heat of the moment, maybe while watching Jeopardy, or playing Trivia at the local bar. These things happen.
I do understand the argument of it’s not in the DnD rules or that there is not a corresponding good benefit of rolling a 20 to offset this. I’m fine and supportive of those arguments. I just don’t understand the argument of not being realistic.
Your examples are simply wrong.
DC is there to show how hard it is from the start till the end.
Critical miss means something that wasn't there at first suddenly happened during the fight. It always translates that way.
5DC means it's so simple and basic a commoner could do it.
If your low-level character has 5 points in corresponding skill means he is either naturally super good in this kind of work (20 in the ability) or has good knaks for it and it's part of his everyday professional practice (16 in the ability+proficiency)
So now to your examples:
1) You practically can’t snap a lockpick if you’re doing it right, even if it happens to have a flaw. It’s made of metal and lockpicking with a lockpick doesn’t use brute force (if you wish to take a look at some real lockpicking here you go
https://www.youtube.com/c/lockpickinglawyer). If the brute force suddenly came into play it means the lock happened to be more sophisticated than you thought so it’s simply not 5DC from the start. Also lockpick has its flaw before the start, so you are either supposed to be able to examine it before even starting working with it or you anyway get your higher DC for working with broken tools beforehand.
2) The little stone didn't crawl into the lock while you were trying to open it. So it's a damaged lock from the start, which is supposed to be known by your DM beforehand and it is also not 5DC.
3) I highly doubt that you have problems with recalling things that you actually use all the time as part of your professional practice unless you have some health problems or temporary condition causing memory problems, which is again higher DC beforehand. I already covered the question of remembering stuff in the OP post:
If you don't remember something from your studies, you can just spend some time trying to remember.
