Most of the guys that hates seniority are those that pretend to get inside a major airline to be captains right from the start. Big egos instead of big brains. They dont care if they by-pass 100 o 1000 workmates. Most hate unions and will rape their own mother just to wear 4 bars. Why dont wait just like everyone?
Seniority is the only thing that will protect your career as a pilot. On major airlines, where you are FO 8 to 14 years seniority absolutely necessary. Is the only system to avoid injustice. Or to avoid mother rapist. When your turn comes you will be upgrade (Off course only if you pass the command course).
On small or new airlines that expand rapidly is a different story.