Maybe I'm thinking of the wrong type of connector, but when I see something like Campfire's connection to their IEM: https://campfireaudio.com/
I see a connector molded as one with the shell. The strain should all be in the actual cable itself unless you literally throw these things on the ground with hulk-like force.
Just check out "Shure se215 mmcx issues" on Google. From free spinning the mmcx eventually started cutting out, even though the mmcx was molded in the body.
It also looks like the mmcx on all those earbuds is not molded in the bud, but just kind of glued on.
I don't see cables add inevitably breaking down. I've had 10 year old cables that still work like new. The secret is just treating the earbud better. If you often get the cables tangled then yeah, they won't last more than a few months. If you get a circular earphones case from the dollar store like this ... https://www.google.com/search?q=ear...hWNE4gKHWHuD9sQ_AUoAXoECA4QAg&biw=360&bih=630 ... And coil the wire around three fingers lightly before putting them in, you cable will never break. You will also have time not having to undue knots everytime you want to listen to music.
At the end of the day, I think a one dollar earphone case to protect 150 dollar earbuds is worth it, much more than relying on a false sense of security you get from mmcx connectors.