I have been doing my own services and repairs since I was a kid. 30 years of Ferraris, lots of Porsches and now Macca. I am not exactly low budget and it would be great to have a comprehensive tool...... but it has to make $ sense. Unless the car is an absolute POS, the enthusiast is going to use it a couple of times/year.
During my 2 year service, I needed to bleed the brakes, but one needs the tool to do it properly. I let the dealer do it. I think I paid $350. I would have loved to DIY...... not so much for the $ saved, but working on these is part of the hobby for me. $2K+$600/yr just doesn't make sense for the use I would get.
If someone puts together a comprehensive tool that they can sell for $500-$1000 and no ongoing fee BS, they would sell a bunch and corner the market.