"Simply cramming more pixels onto the same sensor and processor usually just increases noise and so on.
If if is the same sensor and proportionate pixel quality, you lose nothing by adding more MP should you take that higher MP version and downsize it to the lower MP equivalent before comparing. If it were the same sensor and processing with the only difference being MP, all else would be equal, so your statement is not true - higher MP in that example would always be the same or better with regards to image quality.
Taking the same sensor/processor and "cramming more pixels" onto it increases pixel-level noise, but you gain it back *and more* when you down-sample to match the lower resolution comparison. The reverse is not true, so if you were to up-res a lower MP image to try and match a higher MP image it would be much worse.
Modern sensors are all pretty much at the limit of what physics allow, therefore when the higher MP versions are down-sampled to match the lower MP versions, you are *never* left with a worse image (all else equal), and it hides noise better among other things. You also of course get extra benefits like much greater resistance to moire and less destructive post processing, as well as usage of the higher MP when you want it (cropping flexibility, etc.)
My point was not “all else equal”. We are comparing Pro model with Zoom. And the benefit of more MP is well know to be over rated. Google it and read for yourself. Here is one article from Digitrend.
I am aware of how it works, as well as the in-depth sensor physics behind it all. The article you posted is not well researched and perpetuates several myths, especially with the very basic/elementary explanations they are using in order to make broad, inaccurate generalizations. The benefit of more MP is most definitely not over rated, all else equal (even if you forget the Pro model and look at two 1/2.3" sensors). There is a whole lot more that matters, such as things like well capacity, bit depth, microlens array, how the ADC is handled, etc. It is not as simple as saying things like larger sensors are always better, and anything more than 12MP is a waste - there is so much more to it than that.