There is no reason to assume that the use of a word implies a meaning behind it. Sometimes, words are markers or labels. Internal is such a use. The internal styles are largely Taoist or "may as well be Taoist" styles. Given the Taoist view on labels, where most martial styles will view many things associated with Yang as good, Taoist styles play no preference. This relative difference makes them more cognizant of yielding perhaps, perhaps not. Any throwing method uses yeilding as well as pushing, coincidentally(not) taiji makes extensive use of both.

So, the term is not useful as a descriptive term. It is only a marker, I say "I do internal kung fu" and you know what general thing I practice.

If you ask, "How do you do an internal roundhouse kick", and I can say, in my style there are a few who do the roundhouse kick in their set, the main difference is in a waist motion common to some lines of Chen style and our style, among others. Aside from that, it's like other roundhouse kicks, but it is distinctively internal. If you say "but that's not internal, it's external", I have to point out "It's from a Taoist style, it has the specific mechanics that the internal styles favor that other styles often don't use," you retort, "but that's an external description, that's not something removed from the external," I say, "How can you remove the internal from the external?" But I'm just being cheeky, the term is not descriptive, it's a marker in modern usage, and nothing more.

Language is murky, not all terms require specific content in their makeup, words often gain meanings and shed them. Internal is a marker, not a descriptive word, and people will continue to use it, those who argue against it will continue to cry tears of impotent rage.