That's one way to go. You can also take the path of radical simplicity: only include what is absolutely necessary, and what is resilient enough to work in wide situations. To make a tool of the highest quality.
Sometimes a constraint like that can lead you to solutions even better than what you started with.
Or you can write a robust design that starts with radical simplicity that is at least functional, and then progressively enhance the page with whatever features are currently available. The user shouold at least be left with something usable if the Javascript or CSS or font doesn't load.
This modern trend that tries to pretend that the User Agent will always support various features or that they can simply assume that network errors never happen just makes sites look shoddy and unprofessional.
Sometimes a constraint like that can lead you to solutions even better than what you started with.