Searching competitive or sound-alike uses of a proposed brand name is an automatic part of corporate nomenclature work. As a rule you cannot claim as a trademark a name already in prominent use in your business sector, e.g. you can use the name McDonald's for a new motor oil or wool socks, but not a new hamburger restaurant.

Securing relevant URLs is also part of due diligence -- even URLs that could be turned against you. Political candidates, for example, purchase not only JoeBlow2020.com and JoeBlowUSSenate.com, etc. but also DefeatJoeBlow.com and JoeBlockStinks.com. United Airlines obviously wishes it had snapped up untied.com.

I am very surprised that Marriott appropriated a name already in use for 10+ years in the travel / hospitality sector, and did not nail down the relevant URLs. It sounds like either sloppy detective work or poor foresight. And all this for a name that is decidedly imperfect / weird. Some top exec must have really liked it.