Welcome to the forum,
I think there are various reasons. Which could be ranked by priority.
1. In my opinion, you need really aggressive marketing to get noticed these days. I think that's a little missing from Mixcraft. But things are slowly getting better. To get new users, you have to stand out. Especially because old, long-standing DAWs have a lot of forums, tests and discussions online. But at the end it's all old stuff from the past.
2. Many DAWs come from the past, many users have been using them for decades and have settled on them with workflow, hardware, etc. In order to get a user to switch, you need very good USPs. Mixcraft has some like UX, performance, the team itself. The first choice for users who are looking for exactly that. But I could imagine a few USPs that could also inspire users of other DAWs. USPs also support marketing under point 1.
3. Due to the size of Acoustica's team, there were still some missing features in the comparison before Mixcraft 9. From that perspective, I thought it was right to stay a little under the radar. With Mixcraft 10 the guys have caught up very well. Mixcraft 10 ist really good I think. I would never switch back to Logic or Cubase. For me, Mixcraft is currently the best DAW. I previously used Logic, Cubase and Samplitude. I currently still own Reaper, but I don't use it anymore. That says it all
I see a few more things there, but the Mixcraft guys probably see them too and these are not the reason for the missing visibility on the market. You don't miss anything with Mixcraft 10 and you get the perfect workflow. Anyone who has ever used Mixcraft definitely doesn't want to use the other daws anymore.
An interesting question is whether you really want to grow so aggressively or whether you prefer to grow sustainably and slowly. Maybe this is the reason why Mixcraft, the team and the community is currently so great.
But that's all just my opinion
Patrick