At least in some circles yes. It is very much only sync service creative professionals use.
Mainly due to conflict resolution, corruption and version history. It still has best implemented “online only files”.
Think 10 person design studio all working in one big studio “Work” folder.
So while the clients got bloated Dropbox still has edge in essentials. People trust it unlike other services some of which are straight up infamous for loosing your files like iCloud or corrupting them like adobe creative cloud.
And block-level sync. Many sync services only do file-level sync.
I don't suppose you know if any creatives use SyncThing? Curious to know how it compares
I think that SyncThing does not solve other reasons (besides sync) why companies use Dropbox and thats backup and public download links. You can set up SyncThing with one always on instance on your NAS (we used to have that at work) but by that point it is quite technically challenging. And you still need to have some way to deliver downloads. For people like photographers something like Dropbox is probably harder requirement than Adobe.