It's shytty Hollywood script writing. Combined with the decisions to include Quavo and Kevin Bacon's daughter, Narcos really dumbed down the story.
In reality, there was no meeting with Felix and the plaza bosses where they had a vote to join him. He was the Godfather, not a democracy. Felix got knocked to prison, then had one of his lawyers conduct the meeting in which the Guadalajara cartel was split up. HE (Felix) decided who would get which territory, except the Gulf, which was never under his organization. He actually still controlled the organization from prison until they moved him to a max security prison and he lost direct contact.
Felix went to jail in 1989. The Gulf nephew (Juan Abrego) had already been running the Gulf since the 70s, not the old dude who had turned over power many years prior. Also, Amado was not given Juarez until the early 90s. Tijuana was given to his family (nephews), the Arellano Felix family (AFO). Sinaloa was given to Palma, Chapo and another dude. Rafa's brother was given Sonora. The SInaloa-Tijuana wars kicked off in 1993. Los Zetas started back in the late 1990s.
Why Narcos went down this path is puzzling. The timeline does not add up at all. They are taken wayyyy more creative license, basically laziness, than the Colombia series. The quality has been downhill since the end of season 2 Colombia.