Most of the people playing these rare picks aren't good enough to judge why it would be a good pick or what niche it would fill. Like my Silver and Bronze friends are always telling me "Oh man X champion is fucking great in Y role if built like this", then all it takes is "Ye but what happens when you're against [Extremely popular counter mechanic]" to shut them down, it's like they didn't even think about any other match up outside of the 2 normal games they played on this and just head straight into ranked and are surprised it didn't go as planned.

Or even if they are right, they can't play it how it's supposed to be played. This is obvious if you watch a Caitlyn "counter-pick" to a Vayne and watch her NEVER auto Vayne during laning phase. They gloss over where the champions strengths are and why and just assume it's an auto win from picks and bans, which transits over to their rare picks, they don't look for power spikes vs their opponents, and they don't play variable builds. They are ill-equipped for advancing the meta in a Ranked setting.

These things combined (and surely many other factors) make it so that people picking rare picks or straying from the meta are ostracised and it's not necessarily a bad thing. At that level people should just focus on improving their knowledge of the meta rather than trying to reinvent it, rarely have I seen a positive rare pick turn meta from a low-elo game, and by rarely I mean I cannot recall a single time.

However you should definitely play what you think is fun rather than what you think is meta, just don't try and push it into the meta and try to be considerate of your teammates, especially in Ranked where people might not agree on your Tank Lucian Jungle.