They won’t do that because simple file storage is always “abused” and will have to be shut down. There always has to be stressers to limit use cases to casual ones.
Whatever ways incompatible with business models, not necessarily with hostile/malicious/abusive intent. Maybe "abused" can be replaced with "used for procedurally generated data" or something.
If I rent 2 TB and use 2TB it doesn't matter what I use it for, does it?
I would agree if we talked about Backblaze with "unlimited" backup for next-to-nothing, but this is Dropbox which is rather pricey and also limited to a very specific number of (Tera)Bytes.
If they cannot deliver on their promises, shame on them.
The service offered is something mouthful like "document cloud storage for sharing over the Internet billed for up to 2TB space", not 2TB of raw disk space.
And backend is always S3+Glacier which costs about $25/TB/month for storage and $100/TB for download, so not just that filling up your quota to the brim costs them more than twice as much as the what Dropbox charge for a 2TB quota, but overwriting and retrieving the files is going to seriously hurt their budget. Not your budget, none of your business, but that's how it works, that's why anyone other than them went bankrupt, and that's why they don't try to be nice to advanced users.
Last I heard they aggressively deduplicate across customers and also shared folders count towards the quotas of both sides, at least that is how it looked like to me.
Edit: But most importantly: if you sell me "x units of anything" it is not abuse if anyone use whatever they thought they bought.
I'll discuss it if a highly technical user keeps "trashing" it by uploading frequently changed and unique data for no good reason (like in trashing a cache) etc, but ordinary users, filling their quota to max? No way.
