There was a thread about this on Reddit a month ago. Not really sure how credible this information is but they claim that people at luxury Marriott hotels will do this to provide a more personalized experience.

https://www.reddit.com/r/marriott/co...eb2x&context=3
https://www.reddit.com/r/marriott/co...eb2x&context=3

Notable quotes:

"We try to find anything we can about the guest via Google or social media, especially if it’s a special occasion (anniversary, birthday, etc; they’ll get a different amenity for that)."

"It was my team’s job to find out anything we could about a guest and use it. Examples: if we see you’ve requested extra towels in multiple previous stays, we’ll place extra towels in your room before you get there. If you’ve complained about noise while in your room, we’ll assign you away from elevators or away from guests who may be loud or have kids. If you prefer milk chocolate over dark, we’ll use only milk chocolate for your turndown. If you’re allergic to feathers, we’ll prepare the room feather-free.
List goes on! That’s the luxury hotel difference."

I know for a fact that employees at a USA Ritz Carlton and an international St. Regis have googled me before. However, I have never received this level of personalized service at a Marriott hotel I haven't already been to (though other hotel brands are better at this). Seems like it's either cap or very property specific