The reset on Elder specifically is super weird. There was an LCS game a few weeks ago (can't remember which team) that was pretty much decided on an Elder reset that both teams had very little control over. The game was decided on the dragon resetting and both junglers failing their smite executes. One team (the one in the pit) was able to finish the jungler off before the rest of their team could engage and the game was over from there.
The game wasn't really that close but it was the nail in the coffin. Pro players should generally have foresight to know that contesting = probably going to reset because so many people are juggling the aggro, but it was pretty silly to watch.
I really wish I could remember which game this was. I've checked C9 vs TSM from week 6 and CLG vs C9 from week 7. If anyone knows or I find it on a VOD I'll update the post.
As a side note, Elder's natural hp regen that other people have mentioned is supposed to make it easily contestable. I don't have a problem with that. It's just the fact that it reset so easily when people were still trying to kill the dragon just because it kept aggroing on different people. I'm aware that all jungle camps aggro on the person closest to them and that changing targets too many times will reset it, but it was absurd to watch considering there were 3 champions in melee range of the drake.