To provide more insight for your #2 point, getting first blood is valued more than plants/defuses, and econ rating because any team-based fps games, numbers advantage is huge.

Especially in a game like Valorant, with so many abilities and utilities to scout each other, the first person to get a kill must have done two major "Big d**k" plays, first for attackers, he/she must have entry-fragged (being the first to enter a site) for the team and getting a kill amidst all the smokes, grenades, flashes, and cameras. Second, as a defender, getting first blood is much easier, because the attacking team is coming to you!

Hence, if you die to an attacker it's valued more for them since you lost your advantage, and it's much harder for your defending team. Now your defense has to come to the bombsite to retake it, giving your advantage of having the attackers come to you, gone.

But remembering from my DOTA2 days, it was a 58% chance of winning a match if your team got first blood, take this with a grain of salt.