For the past few years, a growing number of users, analysts, and experts raised alarms about a truth that feels obvious to a lot of people who surf around in web browsers: the quality of Google results is in serious decline. Google disagrees.
“as opposed to” is an idiom that just means “in contrast”. You’re creating a contrast between what they’re actually doing as opposed to what they’re supposed to be doing. “As supposed to” doesn’t work as a preposition and doesn’t actually create a contrast on its own.