I forgot there are two similar threads. I'm going to back away a bit from my position in my post here, but I'll return to that other thread also.
Yes, beginners should get a sound basis in the fundamentals early, or they will eventually be frustrated when they progress to advanced levels and find that bad habits are much harder to unlearn, or find that necessary skills have been skipped. On this I am in agreement with keypeg.
On the other hand, the percentage of beginners that will ever proceed to those levels is very small, and the percentage that practice enough to actually engrain any habits is also small. Many students are sent by their parents for enrichment or resume padding, and for them this doesn't matter as much. An enthusiastic beginning teacher may not have all the skills to start out the prospective conservatory candidate, but might teach a little piano along with a little fun and a lifelong love for music to everybody else, and over time will hone their teaching skills.