Were there other theories that explained why the elementary particles have mass except for the Higgs?

Regardless, the point stands: we knew that something is missing from the Standard model, and we knew that it must exist in a very precise range of energy. If it didn't exist there, it could have called into question the whole SM.

In contrast, we don't know that there must be some kind of dark matter at the 100TeV scale. We know that one particular type that we have thought about could exist, but we have other candidates as well, and there are ways that the 100TeV prediction could also be moved to higher energy levels.

Meanwhile, we don't even know if dark matter is a kind of matter or a modification of the force of gravity or a problem with approximations of Einstein's equations used in practice etc.