It's possible to just do "English" but sites are typically going to either do British English or US English. Not putting the British flag to avoid offense is just hiding the fact that you're localizing to British English to try and avoid offense. (Which doesn't actually seem better to me.) Unless you actually do separately localize to Irish English. But also why not just provide the same text under two flags?
Also, on the other hand, China may get very cross with you if you refer to Taiwanese Chinese at all. How you refer to a language is inherently political, and hiding the flag changes the political statement you're making, but it doesn't eliminate it, nor does making a consistent decision like "no flag" mean you're going to consistently side with oppressor or oppressed.
This is all "types of PCness" and I don't say that to dismiss it or say that I would never do something for the sake of PCness, but mostly to say that throwing out flags seems like a cop-out and not addressing the problems on a case-by-case basis.
The bigger problems are probably countries with indigenous native languages that only exist in that country but are also a minority... many Latin American countries where you might put Spanish with that country's flag but there is Nahuatl or Quechua or whatever. But on the other hand realistically you are only localizing to Spanish, so again, you're just trying to pretend like you've made a neutral political choice by hiding the flag.