There's sometimes reasons for sponsorships, like how Tidal Wave's huge running costs (for a ride that's not always that popular unless it's very hot) are offset by the sponsorship. The sponsor pays part of its running costs in return for advertising.
Same for other rides that have a big build cost, the park might find a sponsor to help offset the impact of the build in its first few years.
Or Alton Towers getting free toiletries in their hotels with the Flume sponsorship
But they have to be unintrusive on the ride experience, the worst is when parks are just looking to make money so start putting sponsorships everywhere. Someone in an office closing their eyes and pointing to a map, 'Ok lets put the sponsorship on that one' and then hunting for the most desperate mundane brand they can find.