"Right and wrong Technique" now that is a modern phenomenon.....good and bad technique was what i grew up with.
We liven an age of visuals, music just happens to be aural, not visual.
Now thumb over the top is wrong? I challenge anyone to listen to a recording and tell me if they have their thumb over the top?
For that matter whether they use their thumb, or one finger, or two fingers strictly alternating.
What about a three finger technique?
Listen to that recording and tell me they are using floating thumb, or the bass neck is at an angle, or their amp is dialed in to these settings, or they are using Stainless steel strings, or flats over round wounds.
The formative years of playing is about using our ears not our eyes.
Youtube, or a video, or a picture book, are all distracting from using our ears to learn music.
The hard part today is making students understand all this, their lives have to many distractions that take them away from learning to listen to music.
I grew up with records, so i listened and learned, i worked out how to play what i was hearing, my tutors worried about my techniques......never me.
The only visuals i had was the music i read or the text books i was given to read by my tutors.
My tutors instilled good habits, and some bad ones i may add, and over the years after i was long finished with their input i worked out what worked for me and what did not, what i do want in my playing and what i do not......and even after 45+ years of playing i am still working out what i want and what i do not in a technique to deal whith what i have to play.....not what it may look like compared to others.