The part where "it's a web app and some video manipulation" requires hiring about a million dollars worth of "at least three developers" (which costs a company their salary plus that entire salary again for insurance, health care coverage, etc) to write and maintain that app for you, plus the at least another million that it'll set you back ensuring that you have all the hardware in all your offices to make that smooth rather than "OH FOR FUCKS SAKE CAN WE PLEASE JUST USE ZOOM WHAT THE FUCK" from every single employee.

Basic video calls? Absolutely, I've done it in a weekend with webRTC. All the other features that enterprise customers require? That's years of work.