Signal added Stories two years ago and they can be deactivated completely. I don't use them but fail to see the problem here. A reason for people to switch to Signal and a non-issue for everybody else.
Signal is a nonprofit; it does not have shareholders.
It does, however have a mission to bring secure communication to a large audience. That means it will add features it expects will expand the audience. I don't like stories in general (they're FOMO-driven engagement bait), but Signal having them doesn't meaningfully impact my ability to use it to message and call people.
https://signal.org/blog/introducing-stories/