The FIA are in a tricky position.
They have to create rules that are financially sustainable and environmentally sustainable enough that F1 is not kicked out of countries that aren't the Middle East.
F1 cars need engines/power units.
The FIA could specify engines/power units that small specialist firms like Cosworth or Judd could supply, and quite cheaply too. But the manufacturers would beat them at that game too, whilst also making it too expensive for such firms to compete.
So, the FIA are largely beholden to the Manufacturers wishes in regards engine architecture.
For the 2013 rules they set up a committee to formulate the rules. With input from Mercedes, Renault, Ferrari and VAG they came up with 1.6L 4 cylinder turbo hyrbids with MGUH and MGUK.
Of course VAG quickly dropped out, and the others agreed, with the teams, that a V6 would be better suited for an F1 car.
A similar situation happened regarding the 2026 rules. A committee was set up with interested parties involved, as well as FIA technical delegates.
The main players were the four current suppliers plus Audi and Porsche.
The latter two were not too keen on the MGUH, so that got dropped. Making the ERS worse.
Then, of course, Porsche stuffed up their entry into F1 and disappeared.
Now we have a formula that makes Audi happy, but I dare say won't make race fans happy.
It's not all on the FIA - the PU suppliers agreed to this, actually pushed for this.