Often, yes. But, you never have to "start over." My recent hook-up in Vegas (at Cosmo) came from a host in Atlantic City (now defunct property) who moved to my #1 property where I already had an established host.

Relatively senior hosts have pretty substantial "pull" when one comes highly recommended.

And, as I mentioned above, you seldom need highest status for the best perks. Point in fact, I got perks at Cosmo that are greater than their highest published tier (I believe "Platinum") based on the host and recommendation.

Different properties handle these issues slightly differently. Some will just "comp" the appropriate highest tier status. Other properties it's more bureaucratic. Other factors like credit also make a difference. Sometimes, if you have a "lousy host" but a good relationship with credit and the casino credit department is "empowered" to make decisions you can get a "bump" in status that way.

Lots of discretionary things happening all the time. Which makes sense, IMO.