The GDPR is about 68 to 90 pages depending on which language you're reading it in. It is trying to be futureproof by leaving measures defined in terms of 'current state of technology', 'reasonable security considering the risk' and other such ambiguous terms.

I run a small business and I like this. Just about anybody can read it and understand what rights and requirements are being set out in it.

The GDPR specifically refers to the concept of "micro, small and medium-sized enterprises" [GDPR 40p1 and 42p1 use this text; they direct member states about the spirit of the law, referring that the needs of such businesses need to be taken into account].

GDPR 58p2 sets out that regulatory bodies in a member state have the power to issue warnings. As in, if you mess up, unless the mess-up is malicious or excessively negligent, you get a written warning and reasonable time to fix the problem. My government (The Netherlands) has taken the effort, as have a significant number of third parties, of creating a legal document of 3 to 10 pages covering some details, and they generally set out more explicitly that you grant yourself a week or so to fix problems without penalty. Whilst the GDPR is intentionally ambiguous in order to try to be somewhat futureproof and remain short enough to read back to back in an afternoon, it's fairly clear this is perfectly fine.

The most strenuous sections of the GDPR involve requests from those whose data you store. If they ask you to supply what data you have of them, and whom you've shared it with, you have to comply. Within reasonable timeframes, and you cannot lie about it. If they ask that you delete this data, you must be capable of doing so, and you must do so within a reasonable timeframe. However, the GDPR is nice enough to grant you exceptions for reasonable measures which nevertheless make it hard to comply. Things like a backup tape are specifically called out. It's okay if data that's been requested to be removed, stays on those. You would have to show that this data is pseudonimized (GDPR-ese for encrypted, pretty much).

Any service which has a hard time supporting requests to explain what data you store and where you've stored it, or which cannot delete it from the main service on demand... should indeed just call it a day and shut down. I don't think a service like streetlend would have a hard time supporting such requests, however.