From what I have seen, which is admittedly limited, textbooks tend to push additional services from the publisher but very little is lost if you don't use those

From what I have seen, which is admittedly limited, textbooks tend to push additional services from the publisher but very little is lost if you don't use those services. Then again, the books I have seen are older (even though I may be reading a recent edition). Anything directed towards more casual learners, I would have a hard time commenting on since it tends to be more the history of science rather than being technical in nature (where references tend towards primary sources anyway), or embedded development (which seems to suffer from a similar mentality as software and web development since it has a software bias).