It's not so much fitness equipment as toys.

Beginners mainly focus on the development of central circumference, and do not need to make too complicated changes. A very simple I-frame can meet the needs.

Experts can clearly know the carving effect of angle change on muscle details, and there is no need to fix the angle, which shows that the requirements for standardization are not high.

So in the advanced stage, its role is still there, but it is not necessary.