This is going to be hard to enforce without some automation here.
Of course I agree with this proposal, and I think there should be a number of terms allowed by our community based on how they use Polkadot.
- Secured by Polkadot
- Powered by Polkadot
- Funded by Polkadot
These three are the most obvious verbs for me.
As for automation, I think an OpenGov NAY bot could help with such a requirement: x.com
Specifically, if a proposer comes to the treasury, and does not include such a phrase in their website, the bot could detect it, and vote NAY.
An alternative to the NAY bot would be some kind of micro-incentive to include these taglines.
I wrote some of those ideas about such incentives to also help us make an up to date ecosystem map: