That may be considered a feature.
ChatGPT seems reasonably concise, Gemini's answers tend to be verbose (without adding meaningful content).
In particular, requesting an analysis of the problem first before jumping to conclusions can be more effective than just asking for the final answer directly.
However, this analysis phase, or similar one, could just be done hidden in the background, but I don't think any are doing that yet. From the user point of view that would be just waiting, and from API point of view those tokens would also cost. Might just as well entertain the user with the text it processes in the meanwhile.
That doesn't seem to be the case any more and there has been speculation this is down to the star method being used for training newer models. I say speculation because I don't believe people have come out and said they are using star for training. OpenAI referred to Q* somewhere but they wouldn't be drawn on whether that * is this "star" and although google were involved in publishing the star paper they haven't said gemini uses it (I don't think).
How does it matter even if the quality is high or low? The point is user data was used without consent.
Additional Twitter data is in my eyes mostly low quality content, that's nothing I would want in a AI model.