It's an argument commonly used by stock android purists. The flaw with their argument is that TouchWiz did not "ruin" android but instead made it more applicable and marketable to everyday consumers.I'm still not hearing how TouchWiz "damaged Android."
Isn't Samsung typically credited in large part for Android's success?
I've owned an android phone since the Nexus One, I used to exclusively purchase Nexus devices for the sole purpose of no bloat ware and fast updates. When I owned the Nexus One, the android market had 40k apps of questionable quality.
If I look back at devices like the Galaxy Nexus and the S3/S4, there is a huge difference in the user experience between those two devices. Stock Android was not suited for the general public, there was just way too many missing features.
At that point, stock Android didn't even have an included voice recording app and i don't believe it has one now either. On top of that, Google expected consumers to find and download the apps they needed from the Play store which ruins the cohesive experience of the OS when basic functionality needs to be implemented through 3rd party apps.
Samsung with TouchWiz turned Android from a bare bones OS with plenty of holes in functionality to a relatively cohesive experience. Performance did suffer but at least users switching from iPhones wouldn't have to go digging in the app store to find an app to implement basic functionality.
Even if you look at stock Android today, things haven't changed much. The camera app is horrific, there's no battery percentage in the notification panel unless it's hidden inside the battery icon where it's invisible and chrome is still an unoptimized mess.
Sure, you get fast updates and great performance out of that box but eventually you have to weigh the pros and cons. In the end, the general consumers are the ones who make the most money for manufacturers and as such devices are tailored to there specific needs.