It's really not, and hey I don't wanna get too into it on here but honestly I cannot take you seriously when you say that melding Tenacity "gimps the role I function as", I am a Tank, a Tank's primary goal has always been and will always be to stay alive and take the least damage possible. Tanks and DPS are two completely different roles. Also, don't you think it's a bit ridiculous that you're judging the content I do in this game based on materia I meld. It's just so crazy hearing you say "no one in their sane mind would take a tank that slots ten/det to any EX trial or Savage Raid"
Because all I do is I run countless EX primals and also Savage raids (most notably had over 100 clears for Suzaku, Titania, and Hades all while relevant, and I've taught groups all 3). Actually, to all of my friends and my FC I have the reputation as the "EX primal guy" haha because I run them and teach them so often. A few peeps on Party Finder have even began to recognize my name and rejoice when I join parties. It feels great.
"The only purpose it serves is to slow down the group that has to deal with you as a Tank." Not only is this 100% untrue, but it's also rude and toxic, I'd appreciate if you stop talking like this. Everytime I'm left at ~4% of my health, Tenacity saved my life, that's how I see it. And imo me being alive matters infinitely more than me doing a few points of superfluous damage. If a Tank's damage is deciding whether a run is cleared or not, there's an issue going on with the DPS to be honest.
Btw, if anyone tries to vote kick someone from a group based solely on materia, they are toxic and the definition of an elitist. I have never been vote kicked from an instance despite my melds because thankfully 95% of the game knows this as well.