Everything else. Seems everyone and their mother are building "platforms", so they can properly lock you in, look at Vercel for example, to get some inspiration where the rest is probably at least aiming.
Not sure why people keep falling for it though, guess it's easy enough to get started that people don't really want to understand deeper, if you can pay someone $XXX/month to not have to think about it, many people tend to go that route, especially if VC-infested.
Thus platforms and SaaS products, seem to be the only way to make sustainable open source products.
I can't speak generally because it varies but is this really the case here? Other posters have commented on missing features and issues with their product i.e. Deno Deploy so is it not willing to pay or not worth it?
You can build Deno or even Deno deploy in a weekend? Even AI can't (not properly).
1. People say things all the time especially online. They might even tweet about their weekend project YET they might still buy it. Not equivalent.
2. If you have to buy it is usually tied to a business reason e.g. make work better or their business and so there's a lot more to it e.g. safety, regulations, etc.