kelco9 It's not but it's the primary fitting factor in especially drivers, frwy woods, hybrids. Face angle and loft you change one you change the other hence why I don't fit with adjustable driver heads. I would hazard a guess that the majority of golfers are not using the correct face angle. This is why Wishon is superior if you know what FA you need with loft/lie it can adjusted and shipped to you correct or you need a L/L machine that you can do the work. Driver hosels for the most part can not be easily adjusted. Tom designs his heads to be adjusted majority do not but consider the cost also.
MoI heft match and TLT are intertwined and the way I fit/buld vs. 1/2" length graduation playing length/lie adjustment and swing weight heft match. Then, add in shaft weight, shaft profile etal you got a lot of factors going on.