I can't recall any discussions directly comparing textbooks with tutoring, but I can recall many discussions that assume in-person one-on-one teaching to be the gold standard, and all other methods are merely cost-effective compromises. It's implied that textbooks, while not as effective as interacting directly with the textbook author, are an excellent compromise because the author's pedagogy can be widely dispersed for relatively low cost (compared to the author personally tutoring every reader).

While convenience could arguably be considered part of what makes something "better", I think it's also commonly not. Like, you might say a restaurant a half-mile away is "better" than one across the street because its food is tastier, even if the one across the street is so much more convenient that in practice, you eat at the less tasty place five times as often.

In this context it's not clear-cut, but even when re-reading great-grandparent it still seems to me to not be considering convenience to be what makes textbooks better:

> Textbooks are by far the best resource you have available for your class work and even though they take the most effort, they tell you exactly what you need to know enough to know what you don't know.

If anything, great-grandparent seems to be emphasizing an aspect of textbooks that's less convenient than a tutor.