I mean that's basically what they're doing. The BUSL license these projects are using boil down to "you can't resell the project against us". But that's a non-starter for many folks and the companies using such a license are the devil.
Yes, there is far too much ambiguity in these licenses. Especially because you never know what will happen in the future. You could be found to be in competition after they launch a new product or new feature, years after not being in competition. At that point changing out their product could be too challenging, forcing you into arbitrarily expensive commercial license agreements.
Certainly one of the reasons why open source is popular in software is that it gives you options for maintenance prices. You can do it yourself or pay any number of consulting agencies to do it for you, or the creators of the software. When it becomes locked to one vendor suddenly the market economics change hugely. Now that vendor can crank the price up extremely high, basically until just before the point your willing to engage in a hugely expensive software refactor to move to a different product.
Open standards were supposed to help make it easier to move to new products, but in reality, it rarely is that clean. E.g. look at SQL, while it's easier maybe to move from one SQL database to another than from one completely custom database to another, it's still a massive amount of work due to details of each SQL server.
