Basecamp is a famous example of this. It's a pretty popular project management software, 56 employees at this point if I remember correctly, probably millions in revenue. It's a tiny, bootstrapped company, no investors breathing down their necks, no IPOs, nothing. And they're one of the few companies who actually have principles, are committed to privacy etc.
The vast majority of companies like this have perfected the lock-in strategy to ensure that their customers can never leave.