Shadowrun is a “crunchy” game, this means it has a lot of rules, and those rules are not simple. If everyone actually learns the rules for their characters, and people don’t do things that are extremely odd, the game can run smoothly.
IIRC from when I ran it, if someone does a normal melee attack (without any magic, hacking, or vehicle shenanigans), it’s like 20 steps, and some people can attack 6+ times per round at level 1.
Compare this to a game where at attack is “roll one die, add one number to it. Is it higher than their armour? Then roll a different die and add one number to it. That’s the damage you deal”.
Edit: Even those of us that love Shadowrun kinda hate Shadowrun. There was also a time when the guy in charge stole a bunch of money from the company, and they didn’t have the fund to pay the people who actually worked on their games.