You start with a false premise:

An example, if there are like 10+ different communities for “technology”, do I really have to subscribe to all of them just to get the same experience I would have gotten on /r/technology?

r/technology was never the only technology subreddit. There was retro, retrotechnology, who knows perhaps something like bambootechnology, cartechnology, etc. So you never had that experience. You had the same experience you would and do have here, except there it was tinted with a veil of capitalism to keep you submissive. What you are seeing now, is the normal, always has been (insert "always has been" meme). The "big pharmas" of the internet are actually the outlier.

As for the task of "clumping" those communities, I'd surmise in the "content fetching" form that would be the task of a community aggregator, like lemmy itself if eventually a "lists" feature is added, or if communities are allowed to follow each other. Or, if we keep the cross-aggregation separate from the content posting, so that it's possible to do both or either witout requiring a super VPS, maybe a webring could do it. I remember webrings from the 90s. They were cool.