I don't think you realize how many US traders that still trade CFDs even if its prohibited. But metaquotes has shut down a lot of the non regulated brokers that these people use. It was a big news a few months back and I found out through these youtubers. What better way to scoop up these customers and offer MT5. Trust me, your broker will be the talk of the financial youtube channels to be the first US based broker to offer MT5 for equity trading. MT5 has been around for a while. As a platform, I think people prefer familiarity. Plus I think they have a very solid automated trading platform that has THE BEST freelance service offered. No other platform you can take your idea to automation with just few hundred. Other platforms will charge thousands...
You are correct. Not only do I not know, but it is not my concern. I was responding to the question about why more equity brokers do not just add this software. My point was it is not economical to just add more.