I agree with many of your points, but I would add that there is/was a reason for wanting MTM accounting:
The lies and fabrications of highly elastic accounting had reached a point coming out of the dot-bomb bubble that people wanted a set of financials from a company that they can then put through a (relatively) simple program, come up with some ratios and trends and make a simple, qualitative assessment based on the company’s own accounting.
The complex nature of many of these “mark to model” assets prevents that - simply because the company does not make the “model” software available to investors. If the software that implements then model were available to investors to run and verify the value of some of these illiquid assets for themselves, there would be a bit more trust in the companies that hold this crap on their balance sheets.
The real solution to this crap would be for companies to cease pursuing and buying assets that are absurdly difficult to value. If they maintained their books in easily-understood assets, then we would not have this mess.
Don't get me started on infinitely flexible accounting ''rules'', or what I call ''feed-the-pig'' accounting. These are at least as responsible as derivatives for some of the financial fiascoes we've seen of late, and they should be excised wholesale from accountancy. Starting Monday. Grrrr!