Im gonna make a really "bold claim" now and say it's because the MP content & experience is in a very dry state with lack of maps and features on top of all the annoying bugs. But definitely not because of stuff like TTK or "game's too similar to CoH1"
Just to clarify: My post was about how boring I find CoH3 to look at. The TTK might be fine when playing yourself, but as a viewer this can be different. CoH has the chance to draw many players in by great visuals and intuitive gameplay. But, despite me playing CoH2 for hundreds of hours and understanding the mechanics of CoH well, I found it odd how many "good plays" top level players didn't take, because they know that they won't be able to kill a low health infantry squad. This is probably worse if you're new to the franchise.
This on top of the SP players leaving the game after finishing the campaign and you get such numbers. Of course I would have loved if CoH3 launched in a way better MP state so we could have kickstarted with much more player retention, but now it's CoH2 launch all over again basically.
CoH2 MP blew horseshit for the first ~6 months and it took almost a year to recover
Let's not kid ourselves, CoH3's launch is worse than CoH2, by far.
On a technical level, both games are/were pretty bad. Which one is better or worse is probably up to personal taste and another debate that has been fought multiple times by now, so I'm not going to re-re-reheat it.
Communication by Relic is really bad and I doubt they realized the extend of it.
Review wise, CoH3 is doing horribly. Overall user reviews at Steam are below 60% and the recent ones are ~36%, showing a mostly negative, which is quite a big deal for everyone that got interested by a trailer or stream and then sees that the game is not just divisive, but definitely bad. No one is going to buy it that way. Even if Relic turns manages to turn everything around in the next couple of patches, the mostly negative label is going to cling on for weeks. It will be hard for Relic to every breach the 70% positive reviews again. I don't know how well Steam reviews worked back when CoH2 launched and I know that the game has been review bombed by Russians due to CoH2's campaign, but filtering for the earliest reviews gives +85% positives? Anyway, I doubt CoH2 every reached the level of CoH3's negative reviews. CoH2 had the chance of surviving by new player influx. CoH3 probably not so much.
CoH3 also lost more players post-launch than CoH2 back then. Peak players dropped way harder for CoH3 two months after release.
There's also more indicators. CoH2 never dropped below the player count of its predecessor, even most positive reviews on Steam are pretty critical, players seem to be concerned about the roadmap and Relic's prioritization.
It's not all bad, but the biggest issue is that players are still leaving from CoH3, and the negative reviews will surely hamper CoH3 bouncing back quickly for months to come. CoH3 is in a worse position than CoH2 back then. Tournaments and streaming could help out Relic a lot (and even for free), but they don't seem to be willing to get replays and observer mode going.