There’s a reason why people say that a good photographer can make a good photo with any camera or that pretty much any camera nowadays will deliver great image quality. Half of it is because sensor size matters less than one might think.
We have all read the endless debates on various forums and comment sections about sensor size, with the predominant topics being Full Frame vs APS-C, where the sensors really do get close in dimensions. The best argument for a Full Frame is that it is the biggest affordable sensor on the market, both in terms of cameras and lenses. The best argument for APS-C is that it is good enough. But, whether the difference in image quality is marginal or negligible, this discussion is mostly of academic interest, because one is buying a camera, not just a sensor. Everything else is not equal and that does matter.
To be able to squeeze out that better image quality from the bigger sensor, one needs to have the skills, both photographical and in image treatment. To be able to take the photos one wants, it would be necessary to have the right lenses and accessories in their system of choice. To be efficient and comfortable while shooting, one needs to have the right features in their system of choice. However, systems are not equal, they have different lenses, different features, different ergonomics. Add to that subject matter - not every subject will benefit equally from a bigger sensor; or add the final output required; or the audience; or the photographer’s idea of what is acceptable to transmit his message or idea or concept. In this big scheme of things, the size of the sensor suddenly becomes just one small part of the equation.
In short, where one draws the line in terms of size/price/IQ is subject to so many other variables and the final result is so much dependent on the photographer's skills, that simply saying one sensor size is better than another does not mean much, however true. It amounts to nothing more than claiming “my wide angle is better than your nifty-fifty!”.