I personally raid for the novelty of the fights and challenge. Having normal modes of say extreme primals was never an issue for me because you would to the normal mode once, and then actually learn the fight in extreme, which even then would only take at most half an hour to learn. With Alex on the other hand, in order to gear up, you had to run each floor multiple times a week to prep for the savage mode, which then takes much longer to learn. When learning the new savage fights they are close enough to normal that they feel about the same, so there is very little novelty to keep the fight interesting while wiping.

As the OP pointed out, I too have seen statics struggling to keep their rosters together. Players cycling in and out is always a part of raiding, as nobody sticks with it forever, but the attrition rate for this tier has been so much higher. I don't know if I can last another tier set up the same as this one.