I think the problem occurs when "reincarnated" users pick up conversations they had under a different user name, as they forget that they were using a previous identity. Some times they try to change their position slightly but the deception is pretty obvious. They also jump straight in and call people they have only just virtually met as right wing extremists, etc. It all paints a picture of the user not being a legit new user.
The telling signs are:
1. join a DIY forum, but post nothing about DIY, not even a first post.
2. pick up arguments with same people they previously argued with.
3 follow the same MO to disagree with everything the "bad" people say.
4. exhibit the same personality disorders of the previous incarnation. (e.g. obsession with rules, "fairness" etc).
It's very easy to spot the personality traits. Certain people on certain spectrum find deceit very hard, while others live in a permanent fantasy, you will find they find it hard to step out of character.
I can understand your point of view, but it smacks of your opinion filtered by your perception.
Can you understand other's opinion.
Some may simply browse for some time, until something that they perceive as wrong or incorrect or unacceptable motivates them to join and offer a different perspective. That scenario fits your description just as accurately as your opinion.
Then there may be others, especially like me, who are accused multiple times of having previous usernames, so it's perfectly natural to try to ascertain how or why these allegations emanate from. In doing so, much research is done on previous posts.
Then there may be others who think about joining, but just observe for a while, considering their options.
So you see, there are many other, just as plausible possibilities for why and how and when people join, that you choose to ignore.
Additionally, your point about previous arguments being resurrected, maybe the users that were entwined in these previous contretemps actually restarted the current contretemp with a new user who they think is a reincarnation of a previous user.
So it's not the new user that starts the current indisposition, but the long-time poster that restarts their argument with the new user because they make a mistake on the real identity of the new user.