Sounds like you are reading NNTP via Email.
Email based mailing-lists & web-forums can implement moderation, but on USENET it is not a practical solution.
Even on mailing-lists & web-forums, true moderation is undesireable because it introduces significant latency which destroys conversational interaction & limits contribution.
Web-forums instead tend to implement filtering based on user reports, outsourcing the task to whoever sees it first. Click "report to moderator" gets offending posts deleted. As such it requires little moderator effort or latency.
Change how you view uk.d-i-y by using an NNTP client (Newsreader) or view it via one of the web forums (HTTP). NTTP clients can filter spam by subject keywords or size, web forums can implement similar filtering (automatically).
They always said NNTP was dead in the mid 1990s, but it seems to survive quite well - depends on subject area.
uk.d-i-y can be frightening at times re questions. However its real asset is the ability to use
Might stop some trying £20 chainsaws as "safe-n-cheap". Answers may be wrong, but that is a risk with Usenet in providing answers from demolish (saniflow) to unvented.
So if you can get HTTP access consider using Google. That way you can not only read groups, but search. A purely NTTP experience via email/webforum is limited.