The Internet is not a "series of tubes" ... It's a packet-switched messaging network. The fact that billions of computers are "connected" to a single address doesn't really mean much other than they've exchanged some messages within the last several minutes (or some other arbitrary amount of time).

You're not wrong: any sizeable web service must distribute to several servers and data centers for performance (e.g. response times and data throughput), and for resiliency (e.g. if a server fails then another one can take over). But the difference is these data centers have a financial incentive to maximize efficiency in both hardware costs and electricity usage (which includes cooling, etc.). Folks self-hosting Lemmy/Mastodon/etc. servers in their basement have much less incentive, and so less effort is put into eeking out every ounce of capability per dollar. Even hosting on AWS/Google/Azure/etc is never going to beat a bespoke data center dedicated to one particular application.

Although they don't necessarily publish this information, at least a data center can accurately measure its energy usage (which tends to dwarf hardware costs...). Also newer hardware will always outperform old hardware per energy usage. For either aspect I can't say the same for the server in my basement ... It's 10 year-old hardware running on the same circuit as the beer fridge next to it. I have no idea how much electricity it uses to handle like 2 users. It's a glorified space heater.

It's all about trade-offs. Fediverse applications value open standardization, availability, and long-term resiliency over efficiency, performance, and short-term profits.

The Fediverse is great, but in the short/mid-term, efficiency and ecological impact aren't things i would expect it to excel at.