What if we have an app that suddenly gets an influx of requests to join (thousands of accounts per day) but we can't meet the demand because we have a limit of only 2k claimable accounts per day?
I mean, it can happen (and it should if we are succesfull). I don't understand the limit, with the amount of resources credits available platform wide we should be able to create more accounts per day...that should be the only restriction (I think).
If we reach the limit (what a great problem to have, right?) then we still have the option to alter the subsidy limit and/or the witnesses can change the sign-up fee.
... and most likely there will be time to react. It's likely major apps have a buffer of already claimed tokens or use a service which does.
That doesn't mean we shouldn't dust off the idea OracleD once had to be able to put together the tokens individual accounts claimed, to use via the same pool/account and maybe with a compensation for each account which contributes (like a token on Hive Engine, the idea OracleD had back then).
Plus there are guest accounts on some interfaces, the idea of light accounts/simple wallets may not be dead and there's OpenSeed project.
I think when it comes to scalability, we'd be good.
And serious interfaces do and will continue to make efforts to look well in the eyes of non-technical persons that have no connection with crypto world. But they need feedback to realize they are not going in the right direction with something.