I'm not following - can you elaborate?
I think the subtext of this particular response to your question is also that Tether is a buck wild part of the cryptoasset ecosystem, being the people in whom the most trust has been placed, even though they have been repeatedly demonstrated to be lying and have obvious and severe conflicts of interest, and it's just a crazy rabbit hole and systemic risk that ought to be discrediting to the ecosystem as a whole. But time and again cryptoasset folks will roll their eyes and say, "This again?"
I'm frankly not interested in taking the time to cite any of this, but if you throw Tether into the HN search, there are many, many credible takedowns of Tether.
* At least, this is how I interpret "store of liquidity," liquidity isn't something you store? It's the property of a marketplace to execute trades readily and at a low cost? So this may be some jargon from the cryptoasset community with some alternative meaning.
And Bitcoin is pretty liquid, at the moment if you market sold $5m million dollars worth of bitcoin on bitstamp you'd drop the price by about 1% and bitstamp is by no means the largest exchange. Obviously not being quite as bone headed as making bulk market order would do better.
... now, how much VTI shares can you sell right now? None. The major equities markets are closed. When the markets are open, sure big equities indexes are very liquid, but many single stocks -- even fairly large ones it would be pretty hard to move $5m in an instant without crushing the price.
If you have $3000 in stocks and you want need $100 you can sell the stock and then buy it back on your next paycheck. But unless your account is over a certain size, you can only do this so many times in a specified period.
Since this restriction doesn't exist with crypto, you can sell and buy back the same crypto 1000 times in a day if you want to (and many bot operators do this)