Besides API features, it won't require downloading 0.5 GB of web browser in order to run.
Sure, you can make it smaller, but how many companies actually do this?
Sure, you can make it faster, but how many companies actually do this? Accountants and product managers don't care about speed or size -- that's a user problem.
Judging by the app sizes I download (and try to avoid), few companies really care about the user experience as long as the basic feature is checked off.
I worked at a company that provided an unnecessary and heavy FE framework (original devs didn't know what they were doing and "just got it out there"). Most of the target audience used used older PCs, and thus slower and memory limited. Some pages required multiple GB of browser memory. We've had this problem for decades because devs usually have well spec'd computers.