Why is it still sound if they themselves could not live and follow their own philosophy? I am wary of anyone who professes something that sounds technically sound, but which they themselves cannot live up to.
That's an extremely common theme in the world. Teachers, therapists, doctors, etc. Often the instructor is completely fucked up, and is trying to cope with that by teaching/helping others. But they still have insightful and good advice, even if they don't follow it themselves. Don't focus on the instructor as some kind of idol that, if their perfection wanes, so does your attention to their teaching. Instead focus on the message and whether it will work for you. Many people find that it does, and it's that direct result that matters.
If you want to learn sword smithing, do you take notes from a sword smith who can barely make a sharp blade? Or a master sword smith who embodies their craft to the highest level? I suppose the former might have some unpracticed insights by stealing them from others, but the latter is where I’d be most interested.
On teachers - I know relationship counselors who can’t even have a functioning relationship themselves, and yes I suppose maybe they have some pithy takes on how to have a relationship and also some theoretical knowledge, but I like taking my lessons from doers.
I don't think that's a fair comparison. It's more like would you want your physical ailments treated by an unfit but talented medical professional or the fittest person at your local gym?
Well to bring in a Christian notion here that is useful: We’re all sinners and therefore destined to fall short, but that isn’t an excuse to not try, and to keep trying.
Or to put it another way: Hypocrites aren’t wrong. They’re just hypocrites.