El Salvador keeps buying the Bitcoin for its strategic reserve. Businesses and citizens can keep using it.
But for getting an IMF loan, IMF (which, to put it mildly, doesn't like Bitcoin) required the end to Bitcoin legal tender status.
Now the businesses are free to accept it or not instead of being required to accept it. That's all. The government plans to keep buying and using it.
The other concept is that it is a good medium of exchange. I think that is not so true because 1) its neither cheap nor easy to buy a lot of things with it 2) a thing that goes up in value is not a good medium of exchange because people don't want to spend it, they want to hoard it.
If you accept that BTC is a reasonable investment, but not a great medium of exchange then what is happening makes sense.
I am not saying that a decentralized token couldn't be a good medium of exchange -- honestly I don't know. But so far BTC is not that.
So... traditional money is good because it forces poor people to spend it? Rich people have no problem converting cash into assets that go up in value and holding onto them converting back at need. It's only poor people that have to hold comparatively high percentage of their assets in something that loses value.
When you take out a mortgage on a house its partly because someone took cash they received and deposited it in the bank. If they kept the cash the bank would not have reserves to loan.