I'm not TW obviously so I can't know their reasoning but I am one of the moderators/event organizers for the /r/mountandblade so I'll give my two cents.
To start off, due to the nature of reddit's system the singleplayer-only community on the sub is able to drown out the MP posts and community pretty easily, and while small, they do exist. As a result most of our multiplayer stuff happens on our discord, where we organize and run the multiplayer events for the sub. These are: Mod Night, an "off season" even where we would give players a chance to play the multiplayer for mods that are otherwise dead in MP/popular with the community, Casual Night which was an excuse to play native battle and siege, and the Calradic Campaign.
The Calradic Campaign is by far our oldest and most significant event, it celebrated its four year anniversary and final event in Warband in March. If you've heard of it before you'll know it's casual, but it fills a niche that to our knowledge isn't really represented in any other kind of event. If you want to see more what it's like here's a video by a youtuber that attended one of our best:
Most of our multiplayer community isn't competitive and likely never will be, but they aren't the same as the drooling SP-only people whining about "animation abuse" that I imagine most of you are picturing. The core players at our events see the same issues with Bannerlord's combat and MP setup that everybody else does. Notably, we have been quite frustrated with the class system and lack of battle mode, as it could require fairly extensive workarounds on our part to make our style of events function in Bannerlord.
As for Taleworld's reasoning in choosing us "first" for a custom host event, I think it comes down to the current functionality of the game. We have a history of hosting casual events with non-standard gamemodes in addition to the Calradic Campaign, meaning we don't necessarily need complicated server tools, specific modes, secondary balancing etc. For a competitive event, they would need at a bare minimum server tools capable of switching the factions for skirmish - in addition they would need to be available as many times as it took a full tournament to run its course. To host a *good* tournament, they'd need yet more server tools, time, etc.
To summarize, I believe they chose us not because we're uncritical of their game (we aren't, and Taleworlds knows this), but because we're easier to host a decent event for with the resources they currently have available. All they need is the gamemodes they currently have available, a server slot, and someone able to run the server for an hour or two at the specified time. As we routinely filled a 200-slot server in Warband I'm hoping the event, which will be using TDM where we would normally use battle, will help Taleworlds see the value of including classic gamemodes and more in-depth server tools for all of our sake.
Thanks and hope I was able to clear some things up, if you've got questions feel free