I think it's more likely that we're seeing the average drift upwards and a non-trivial percentage of the community is less involved than they were in the earlier days of the web, so the active community isn't as varied as it used to be.
The other big thing which is hard to under-estimate is how much the web has homogenized over the years. MetaFilter was where you went to find someone's personal blog, collection of cat scans, etc. and people just don't do that the way they used to: instead of blogs that largely happens on Facebook or Instagram (and it's private), individuals are competing with for-profit content mills and SEO spammers, etc.
HN has followed a similar arc – you used to see more personal tech blogs and open source but now that's competing for attention with major companies paying staff to blog as a recruiting effort. Nothing wrong with that but it feels rather different and it changes the values of aggregator sites.
The other big thing which is hard to under-estimate is how much the web has homogenized over the years. MetaFilter was where you went to find someone's personal blog, collection of cat scans, etc. and people just don't do that the way they used to: instead of blogs that largely happens on Facebook or Instagram (and it's private), individuals are competing with for-profit content mills and SEO spammers, etc.
HN has followed a similar arc – you used to see more personal tech blogs and open source but now that's competing for attention with major companies paying staff to blog as a recruiting effort. Nothing wrong with that but it feels rather different and it changes the values of aggregator sites.