I asked about SV supporters, not BU members.
And your original question:
"Why have SV supporters not been contributing to the BU codebase at all prior to BitcoinSV coming about?"
I don't see how this matters or is anyway connected to your argument. But I'll bite.
Do you remember about... a year ago when Bitcoin Unlimited had a job posting for a C++ developer? I do, because I considered applying and excited about the opportunity to contribute.
However a couple of things that are related that dissuaded me from contributing and even applying for this job.
1) I have a good consulting role already. Why change a good thing? Why would I want to make less money?
2) The behavior of some Bitcoin Unlimited members turned me off. But this is secondary to point 1).
There are likely many other people making good money and also tired of the politics.
And Bitcoin Unlimited is about politics.
Why else would they support creating a client for something that is clearly not Bitcoin?
It's obvious that BCH cannot be used as CASH since there's no way to provide cryptographic proof of accounts paid and received in a timeline, backed by PoW.
Whatever BCH is, it's not Bitcoin. It's something else, and it's certainly not possible to use it as a CASH accounting system anymore due to LTOR.
You can keep the same name and pretend all you want, but it's obvious from the outside to the hundreds, if not thousands of us "silent supporters", that Bitcoin Unlimited supports something that is obviously not Bitcoin.
Why the hell would we get involved earlier when it's plain to see?
We finally have some companies with the gumption to say they will scale the software and provide a rock solid Bitcoin protocol foundation for us to build on top of.
It was so disappointing to see precious time wasted by BU members even pretending that LTOR has anything to do with CASH usage and even resembling Bitcoin.
It's shocking that we even have to explain this. BCH is NOT cash. Cannot be used as cash. And whatever it is, it's also not Bitcoin. The white paper is crystal clear on what's intended behind chronological ordering.
Frankly, it's false representation to call the group "Bitcoin Unlimited" anymore. When really you mean "Not-Bitcoin Unlimited". Or being generous it should be "BCH Unlimited" or "Mostly Bitcoin Unlimited".