It's a time/cost tradeoff and for me personally $4 has been fine for out-of-the-box syncing between clients for the last ~2 years of using just the one vault. It's now $8 for 10 vaults (I only recently added my second), which is still a relatively insignificant amount considering I spend more than that on toilet paper.

> if you use Obsidian you will probably have more than one vault.

Why would anyone ever want to use more than one vault? I just use different folders. The only reason I can think of would be if you are using Obsidian for work where you aren't allowed to use unapproved services.

Just me perhaps, but I have three. Personal, Work, and Shared. But only personal and shared are synced as work stuff needs to stay on the work PC.

I use Obsidian as a distant secondary notetaking app.

I use one vault per video game. I don’t need to clutter up a vault just so I can link from a page on Art combos in Xenoblade games to a page detailing all the random things I need to pick up around Hyrule to upgrade this or that piece of armor.

I use Obsidian and don't have more than one vault. What a weird thing to claim.

I don't think you know what the word "disingenuous" means, and I advise you not to makes such personal attacks in any case.