Background
For reference: https://www.amazon.com/Friendly-Introduction-Number-Theory-4th/dp/0321816196
Chapter 2 starts with discussing Pythagorean triples (PT), which is an ordered triple $(a, b, c)$ such that $a^2 + b^2 = c^2$.
It further shows the existence of an infinite number of such triples, by showing that given $a^2 + b^2 = c^2$ and some $d\in\mathbb N$, then $(da, db, dc)$ is another PT, and shows a simple proof.
Then it states:
Clearly these new Pythagorean triples are not very interesting. So we will concentrate our attention on triples with no common factors. Primitive Pythagorean triples (PPT).
Question
Why are PPTs more interesting? I understand that these are going to be rarer, but do they have some sort of application that regular PTs don't have?