I'll posit that it is less eco-freindly for a user to run two power supplies at home vs. one and that all of the extra materiel that goes into a Mini or Studio (e.g. aluminum structures, etc>) are all superfluous and could easily be eliminated. I have zero interest in adding to the energy expenditures required for the extraction and production of manufacturing materiel. Case in point...LOL, no, nothing personal. I just view it as environmentally unfriendly. Mini + Monitor seems better, if either fail they are easily replaced. It makes no sense to me that there isn't some kind of switch or part of the main board that would allow a "dead" or no longer useful iMac (processor wise) to function strictly as a monitor.
I disagree with you here. Yes, under very basic use scenarios one might have an iMac for 10 years of daily driving. I think those people are outliers. "Power users" should never have bought an iMac in the first place. A far more like scenario is, as you mentioned, is it becomes too slow for daily use, but as discussed, Apple does not build in any functionality to continue using the screen only as a second monitor. There are probably a ton of 5k iMacs around that are considered too slow to use but the monitor is functioning perfectly well. Couldn't we could all use a secondary market of 5k screens?
I get that people like AIOs, I just don't have the same opinion for the reasons above.
Aluminum production, alone, currently contributes ~2% of the total greenhouse emissions globally...
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In addition to being an energy-intensive process, aluminum manufacturing contributes approximately 2% to global
greenhouse gases (GHG), equivalent to roughly 1.1 billion tons of carbon dioxide. More than half of GHG emissions related to aluminum manufacturing come from the generation of electricity used in primary aluminum smelting. A transition to carbon-neutral aluminum is likely to require significant capital investment in decarbonizing the electrical grid and in specific technologies used in primary smelting and recycling.
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...from...
Congressional Research Service
"U.S. Aluminum Manufacturing: Industry Trends and Sustainability"
October 26, 2022
That Apple were to produce a display that acted as the master power supply and modularized their M(x) boards to slot into a non-aluminum display would be the most eco-freindly solution, IMHO.
Win-win, AIO users are satisfied that their desks are clutter free and employing a single power supply, and "upgraders" can easily repurpose their displays with next-gen M(x) modules.