At a certain point, does it matter or is this just academic debate on what the definition details? I personally prefer speaking in person, frequently with a "funny voice" or mannerisms. But while I encourage it I don't expect it of anyone else. Occasionally as a DM I'll prompt people to speak in person, but not everybody is okay with it and that's perfectly fine.I was just starting to write that in my in-person group we have a range of players, from "funny voice and all" to simple declaration of actions. And they are all playing a role, in different ways.
I don't personally think you're role playing if you only look at your PC as an avatar that has no goals or opinions based on the character instead of the player. That doesn't make it bad-wrong-fun any more than playing a Tomb of Horrors type module that's designed to test player skill.
I mean, back to the OP. Long ago in a post far far away, I wrote that we role played our PCs going back to 1st edition. I was told, basically, that it was hard to believe that we did that without guidance from a book which is a big part of what I've been pushing back on. Then there's the segue into the idea that as long as your avatar is a PC with specific rules that you're role playing. To me that definition means that every wargamer is actually role playing because their tokens have in-game roles. I wouldn't call that role playing personally.
But it also doesn't matter. The only goal of the game is to have fun and enjoy the company of your fellow gamers.