This issue can have very varied results.

I know of cases where the booking was guaranteed with the account holder's credit card in an online booking, with the second person added, where the hotel had no problem - particularly if an express checkin / checkout were requested.

Where this may work significantly less well is when one is required to show a passport (not uncommon out of the USA) or other positive identification on arrival, and the account holder never shows and presents a passport / id. It's a classic "YMMV" situation, but technically, it's not supposed to happen.

If one has a mutual fund account, it of course will work - but there are, AFAIK, only two ways to have a mutual fund account: have an old mutual fund account that is "grandfathered" in, or to have an HGVC membership with two names on the membership (a number of memberships render a lifetime status with the possibility of establishing a mutual fund, depending on the level one buys in at and the involvement of two people on the purchase documents.) The mutual fund account used to require the people involved be married - I don't know if the HGVC option requires that - and show a marriage document.