That isn't a use case for *Bitcoin* in that it's something Bitcoin doesn't actually accommodate on a fundamental basis: Bitcoin nodes don't need to store or provide access to historical blocks to operate.  They only do today (to the extent they do, many don't) to aid new nodes coming up securely, but in the future that will be accomplished via other means because transferring terabytes of blockchain to process and throw away whenever someone start a new node won't be sufficiently viable.  So not only do you have to worry about it, it'll be inevitable, except in the sense that perhaps there may be some archive someplace or another that has the historical chain and might make it available to you at some high cost.  But if that's good enough you could put your data on archive.org today or just put it anywhere on the internet and let the common crawl pick it up.  This file storage stuff will hasten bringing the day forward when the historical chain becomes hard to access, because people will store illegal data in it and then node operators will be forced to shut down or face prosecution.  Already I'm being sued over accusations that I ran a node that distributed copyrighted data hidden inside transactions.  (so, please, preface any response that this is a speculative concern with a credible offer to cover my legal expenses)

To the limited extent Bitcoin accommodates it in practice today it's _exceedingly_ inefficient for it in the sense that the p2p network doesn't provide random access to the chain (and presumably won't be due to the abuse potential) so unless you don't mind downloading and processing a terabyte of data over the several days to retrieve your kilobyte of data it isn't available to you already from the network. Not that anyone doing it cares, but it's also a abuse that was expressly argued against by Bitcoin's creator.  It's also the case that other blockchains that care less about security or decentralization can do the same thing for radically lower cost (still a dumb idea to use a blockchain for this but if you must then almost anything else does it better).

At the moment there is some webpages that provide access but those will be taken down after their operators give up wasting their money on them (or get tired of the issues with illegal content on them)-- and in that case you're really counting on the websites to provide the service. No different that the *prior* sites that have done "files on the blockchain" in bitcoin (which has happened several times in the past, the files then are practically irretrievable now to anyone but an expert developer).

And that's all before getting into who is behind these companies and what they're doing with the money people pay them to perform transactions for them...

As an aside the data you're talking about doesn't make a lot of sense to store this way:  E.g. "seed phrases" -- because the stored data is public the *only* security for it comes from the private key used to encrypt it.  You could instead skip the stored data and derive all the bitcoin keys and website passwords from the same key with no storage.