You're probably right about that. Although I can point to one very specific way the olden days were better: a Google search used to turn up lots of forum posts, which are often the most useful results on a given topic. These days I almost never see forum posts of any kind turned up a search results (except stack overflow, thankfully). I'm not sure what caused the change but I find useful information is much more likely to be buried by low-information wikihow-type results and corporate landing pages.

Possibly because most forums seem to have died? Or maybe they died because they got excluded from search results?

There was, if anything, more search engine spam then. It's just that you got the tools to remove it yourself and then after 12-15 tries you got beautiful search results. Now they've gotten rid of that refinement process in favor of initial results that aren't spam but also aren't that exciting.