One of the things that makes jj worth trying out is simply the fact that it is different than git, and having exposure to more than one way of doing things is a good thing.
Even if you don't adopt it (and I didn't), it's easy to think that "this way is the only way", and seeing how systems other than your own preferred one manage workflows and issues is very useful for perspective.
That doesn't mean you should try everything regardless (we all only have so much time), but part of being a good engineer is understanding the options and tradeoffs, even of well loved and totally functional workflows.
being a good engineer is also understanding when something is a waste of time because the gain is insignificant 99% of the time
Using "good engineering" as an argument against learning is definitely an interesting approach.
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I think siblings point needs to be made more sharply: this could've gone somewhere good, "I evaluated it and found the gain was not worth the cost to change", but instead went to "the gain from a change is insignificant 99% of the time, so it's not worth understanding it".
The latter is poor engineering.
It seems like all of your comments are like this. Consider stopping that!