Words lose their meaning when overused. That's the one reason that to me, it feels disingenuous. When even the smallest thing is "really amazing", everything is "really amazing". Result being, whatever that person says has very little worth except when something is clearly detrimental.
That alone would be manageable. Yet, this behavior is often expected from others too, which creates an environment that, at least to me, is incredibly suffocating. What's worse, such an environment caused two problems for me:
First, by upping the average of "relatively perceived as positive", objectively neutral people are perceived as negative. I've actually had colleagues go into emotional distress and vent to me over this.
Second, it at least seems like overly positive environments are afraid of criticism and critical people. As a critical person myself, it has been incredibly difficult to navigate such an environment and it lead to me essentially becoming an assembly line worker who "just shuts up and does their job". Also anecdotal, without critical people, going into the wrong direction either ends up being corrected very slowly, or not at all (and given how multi-dimensional work tends to be, going into the wrong or nowhere-near-optimal direction is very likely).
As a result, to me, no feedback at all is only slightly worse than overly frequent, overly positive feedback.