You are basically asking them: "I love your work. Please add an option so I can use it, benefit from it, then leave and never pay you again."
But its worse than that: if I don't have the security that I can leave, I won't dedicate time to use this.
I am happy to pay for the convenience and to try to create MVPs or proofs of service etc.
Anyway, it hardly matters what I think. Imagine what all the students and start ups think when they see it.
If you want control, you don't use a closed source saas RAD.
I would not use the product for myself. I would hate been locked down.
But I can see the value for others. For some, having one easy but clear solution is the important value.
That said, I agree with you that it's probably not their best approach right now. Even if it pains me to say so :)
So in a sense, Anvil is valuable at its price point for just as a web prototyping service. Most new developers obsess on things like "scalability" and "MVC separation", etc and in 95% of cases their creations never ever generate enough traffic to warrant any of that. I see Anvil as a tool that would allow developers to sketch out an idea, quickly iterate features based on feedback, and when warranted, move to a full production stack.
I don't know any actual numbers, but I think DHH and basecamp almost certainly profited from the popularity of Rails. That's probably up for grabs, since integrated web environments in non-js languages may become a big deal over the next decade.
The fact they are built with RoR is an implementation details. 37signals was very good at communication, Ror or not. Their blog and books were fantastic.
ROR as a FOSS may have helped, but I doubt it was instrumental.
EDIT: I agree with you that the product is good, and that the communication was excellent, but I disagree that the success of ROR was minor to the success of that company. It brought a tremendous amount of attention.
It does make figuring out your business model more complicated, but having SOME story for what will happen if you go out of business or start being a bad actor is something you need to figure out.
It isn't impossible though, our SAAS is Open Source and we survive, though yes, some customers do choose to self host. You just end up with fewer enterprise customers and more smaller clients.
But let's be real, if it became open source, I would just host it and never pay for it. They would have to do more work for less money. Hardly fair.
They can always start with a strong commercial offer, then later address the user locking issue. For them, I think it's a way better strategy. FOSS first is very hard to monetize. The Libre community is a terrible customer.
Doing it the other way around is wrong.