Most of the time we need to host our own servers for licensing issues, you might need to consider a "on premises" option if you want to be an viable option for a lot of studios.
The incumbents need to cater to existing customers with a need to host their own servers for licensing reasons; but this forbids them from using cloud native features in the core of their products.
There may well be space for a newcomer to make a cloud only product targeted at the subset of studios that have the legal ability to use the cloud. Instinctively, there may be some useful features around large files which are possible in the cloud but impractical in an on prem environment.
You definitely have a point reg vendor lock, we've planned for this and Diversion will be able to run in any cloud and on-prem in the future (we are running it in containers now).