[Ogedei]

And to this I will add: It's hard to teach yourself something you don't know, even if you have videos.

How many people post videos of their lifting form here for critiquing? How much self critiquing have they done? How much reading on form have they done? They still want opinions on what could be improved.

So could you teach yourself to punch like it is done in Karate? Probably, would it be more beneficial under a Sensei? Yes. Having a master watch your form and offer changes is invaluable. This goes for every sport.