Adobe is the worst offender. I just checked and I have no less than 8 Adobe processes running on my macOS machine, without any Adobe apps running, and with all of the settings to run in the background or sync stuff turned off. I even have a script to nuke all of the services they install that I run every once in a while, but they just come back after a while. It's literally malware. If Photoshop and Lightroom weren't the best at what they do I'd be gone, but sadly they are.