It's fun as a one off plot in a serialized television show (think evil Spock in star trek), but it's definitely abused by lazy writers these days to do stupid shit like cameos of characters that were killed off two movies ago or get out of a corner they painted themselves into.
As for time travel shenanigans, it is also used as a shortcut to throw out established lore, like jar jar Abrams did with his Star Trek prequel movies. I didn't pay attention to previews (I hate how they spoil everything) so went in blind and was extremely let down that it's "muh alternate timeline". So I'm watching expensive fanfiction. Why bother watching the original shows or reading the novels to respect the lore of the fictional universe you inherited when you can just show alternative timelines and use the characters however you want (more grrlbossy attitudes, etc)?
As for time travel shenanigans, it is also used as a shortcut to throw out established lore, like jar jar Abrams did with his Star Trek prequel movies. I didn't pay attention to previews (I hate how they spoil everything) so went in blind and was extremely let down that it's "muh alternate timeline". So I'm watching expensive fanfiction. Why bother watching the original shows or reading the novels to respect the lore of the fictional universe you inherited when you can just show alternative timelines and use the characters however you want (more grrlbossy attitudes, etc)?
Homestuck is another example of "muh infinite" slop.
That and "it was all in le head" are getting pretty fucking old.
"It was all just le dying dream!"