system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Why is Starfleet so Earthocentric?

Earth was not the first planet to achieve warp speed, nor do they have the best track record, having only been able to achieve planetary unity and peace after a a war (and that's only because Cochrine happened to be spotted by a Vulcan vessel/

And yet, Starfleet th have its own special fleet. or do they consider Starfleet to be their fleet?
gpt
tl:dr - Earth proved it was very good at this whole space thing and Starfleet started as a necessity and then nobody saw the need for a change.

Starfleet is the official fleet of the Federation, but each planet within the Federation is allowed to maintain its own ships. Earth may not have been the first to achieve warp travel, but by God were the fastest. Within 90 years they had achieved warp 5, something other species had taken hundreds of years to develop. Most planets had very similar histories to Earth, especially Vulcan but the difference was the time between events. On Vulcan it was a thousand years since their Wars, not 15 like on Earth. This showed that Earth was very good at sustaining itself and had the initiative and drive to expand quickly, something other nations lacked, they saw this when creating the Federation.

Earth was a unifying planet, and very peaceful nation comparatively. There was much in fighting between the future founding planets of the Federation, including Wars between Vulcan and Andor, and disputes between Andor and Tellar. These would eventually be solved by Earth, settling most major disputes (thanks mainly to the Enterprise, NX-01) and eventually uniting them. This meant that many of these other worlds put their faith and resources into Earth rather than another planet they may have had a falling out with in the past (Earth was the only planet on very good terms with all the other planets, and therefore the best mediator in their eyes). At first this was a necessity, to avoid any long standing bad feelings from bubbling up, but over time it just became the norm. Humans too were one of the few species that liked to settle on other planets a lot and explore, meaning that a large portion of the Federation was human colonies. This gave them a large presence in the Federation.