Selling subscriptions is not the reason to also offer Logseq DB. I recommend you read the original announcement, as it explains the reason for adding a mode (next to Markdown and Org).
I agree that it creates a type of (unintentional) lock-in. But as with most things in software, it’s a trade-off some people are willing to make. Those who don’t want to make the trade-off of storing their notes in a SQLite file, should just stick to using Logseq with Markdown or Org files.
The tools you link to look interesting for syncing SQLite files. I hope the community will experiment with them and document how to properly use these tools.