There is robosats (bitcoin lightning fiat exchange). The founder rejected using clearnet to make it impossible for the site to collect user data (or metadata). Also to protect and hide the server of course. IMO, if you want to protect and hide your server, or if you want to self host without opening your modem ports, using Tor can be useful. Ps robosats is good for society and it's concept and UI are very interedting IMHO