Should competing on a two year old be allowed?

Co
I am a horse owner, and I firmly believe and side with the information that says that horses are not done maturing and growing at two years old. Heavy duty activities like racing, jumping, barrel racing, cutting etc. are very hard on an animals body, especially one that hasn't finished growing.
I have done jumping before, but my animal is twelve, not two years old, and while there are two year olds out there that are bigger than my pony it doesn't mean that they are ready to compete. 
Poll question:
Should there be an age limit on when you can start showing your horse in these forms of competitions? 
Alternate question:
Should the age limit for racing horses be increased?
http://www.equinestudies.org/ranger_2008/ranger_piece_2008_pdf1.pdf
If you aren't much of a horse person that's okay😂. You can still give a well educated vote if you look into it. 
While I'll remain of the opinion that it is incredibly harmful to compete in these sports on a young, still maturing horse, I am more than willing to discuss and look at any evidence supporting an opposite stance. 

Vote below to see results!