There is a range of alternative explanations. None of them is consistent with the policy for making laws. Or with what the words say.
Let’s assume I don’t have an IFR rating and I’m flying an aircraft that is not equipped for flight in IMC. I then fly in IMC - heck, let’s assume it’s deliberate. I’ve breached numerous rules by doing so.
What does proposed 91.275 do that is not already covered by the other rules? Am I less likely to fly in IMC if I breach 7 rules instead of just 6? I’m not aware of anyone who weighs up compliance and safety risks on that basis.