why do people ping ? ? ?s all over dead bodies

They tend to do this when you are out of position because they are being toxic shitlords

There's no answer to give to that because it depends on the context.

They use it because it's a "?". They are basically saying "Why?". "Why did you die?" "Why didn't you help me?" Etc.

Riot introduced ping muting not too long ago because people got sick of the ?????.

They spam Ping Enemy missing when you die because it's either ''You did a bad play'' OR jgl ganks and then dies and then there's ''Alive'' Ping because you didn't commit to a fight/you were farming botlane while enemy were doing baron etc etc.

they hate you for some reason

usually they do spam ?? on dead bodies when some one dies very fast as a joke.

lol, ? is "enemy missing" so they are basically saying you're missing cuz you're dead. when they spam ping alive, uhhhh....

I think its like...they expected you to enter into a fight, and you didn't really commit? I'm not really sure on that one.

It depends on the context entirely. Sometimes it's used for missing and sometimes it's just used as a question mark or "wtf?"

Lots of the time people ? ping when someone does a great outplay or something, happened to me last week.

Depends, i got ? Spam pinged by a Morgana who decided it was a good idea to turn around and try and fight five people when she and I (Syndra at the time) were the only ones alive.

Then she threatened to report me and say we lost because I didnt all in and just farmed. Like... sweetie im not going to dive into a 2v5 because our team mates keep wanting to go one at a time to the slaughter house. I did what i could, but im just a Syndra.

If it's the enemy it's because they enemy got bursted, if it's you or an ally it's because you made a mistake, if it's on and objective, the're asking if it'd be a good idea o take it, or if enemies are there. Spam pinging alive on you means they went in, expected a follow up, and you didn't (which may or may not have been your fault) and they ended up dying.

They either didn't like the thing the champion just did. Or they just want to harass them and try to get them tilt for some weird reason (and they are usually tilted themselves already). I personally dislike both uses; most players who did something stupid know it already - there is no reason to rub it in and make them angry with that. Allies doing that are actually doing the team disfavor by doing so by making their team less likely to win.

And if the pings are intended to be actual harassment, well, there is no need to explain that. I just hope that Riot's IFS can recognize ping spammers as one type of Harassment / Verbal Abuse and keep reporting them in that category. Unfortunately I don't believe IFS can detect pings at all.