Implementation detail, automatic builds & tests are a thing in software engineering. But you don't necessarily want players to be on the cutting edge versions anyway, they need the most current stable version which will work with all the other crap they're running.

If the pack is updated behind the scenes, players only update that, which has nominally already undergone some level of integration testing, instead of updating gobs of mods which may introduce new compatibility issues or break version-specific compatibility patches.

Implementation detail. There are a number of ways to handle this, it more or less comes down to what works best for the developers involved behind the pack and its individual components.

Sometimes individual mods have great support, sometimes they haven't been touched since 2013 & have more or less no support, the degree and recency of compatibility patches between everything on the mod graph is all over. Centralized support isn't a bad thing, and it doesn't mean that you can't be as involved, the pack team just has to be good about collaborating with you or directing players to you when relevant. This also depends on if there's one major pack project that you're involved with, or if the user base is sparsely distributed across a large number of packs which aren't run well. If we're assuming permission-based use of mods in packs, we'd tend to have fewer packs which are hopefully better managed.

Credit is a thing, magic internet points are a thing...it's up to the individual mod pack project to sell you on feeling like the pack is also generating recognition and magic internet points for you.