People call Mc Donald’s a real estate fund and feel smart about it, but their moat is in fast food, no matter how they realise their earnings.

That's only a useful question if you're an entrepreneur trying to answer the question of "How do I get in on this game?" The question currently being asked is closer to "Is it a problem for society that so many players are in on this game?"

If every big business is just a moat and/or backdoor for banking, that might be indicative of a problem.

In fact it probably is. Much like internet advertising has to be. You can't have an entire economy based around free services funded by advertising for other free services, you can't have returns generated solely by investing in companies that invest in other investors. Unless massive numbers of private sector backers have been defrauded, the lady is somewhere. Though maybe not somewhere that taxman looks.

I might buy slighter fewer Starbucks, or Fords, or flights if they were no loyalty programs, but I'd be spending zero money on StarBank/FordBank/DeltaBank without the product to go with it.

why is it a problem, if it means that these funds are _more_ efficiently allocated?

For example, buying a starbucks gift card is money being invested by starbucks (elsewhere) and generates a profit. Had the customer not purchased such a card, would the cash have been invested in a similarly efficient manner? Or would it be in the proverbial cash-under-the-bed and not generating any returns?