As this is my first time ever coming across the subject of "antiparticles", I feel a little bit lost. But the tldr at the bottom did me a lot of good and virtually made my curiosity piqued. Now I am all in for understanding what these fundamental symmetries of nature are in the first place. About CPT, from your explanations about the similarity of particles and antiparticles, it looks very logical and probable, I am wondering why anyone would dispute its authenticity at all.

Even if CPT originates from quantum field theory, scientists like to challenge everything. This may open the door to something new, a new vision of seeing our world, etc... This is the scientific method in its full strength :)

The stupid thing is not the agriculture stuff. This is a funny parenthesis slightly too obvious. Hint: please check the links I provided ;)