[boterock]

That's an issue you don't have if you provide source code.

If a customer relies on bad architecture/undefined behaviour, that shouldn't pull back all the other customers that want their subscription materialize into engine improvements.

[pjmlp]

Then buy Unity's source code license.

[Jasper_]

Unity doesn't have a single source code license or price. It's negotiated per-contract and usually has strings attached (e.g. be the first to ship this tech, attend UnityCon and give this demo). They only do it for big companies as well.