Question about the grenade in Half-Life 2

[RealP27G]

In Half-Life 1, the grenade's timer immediately activates when you do a left click. When held for more than 5 seconds, the timer ends, though it will not explode until you let go of the LMB. In Half-Life 2, however, this is not the case as the timer only starts when you let go of the left mouse button and throw it.

Is there a reason for as to why Valve made it so the timer only starts when you throw it? I'm guessing this is for balancing purposes or to prevent nuking yourself when held for too long or because it's used by speedrunners to boost one's self.

[VALVe_installer]

Maybe so, but I am inclined to think that it is more realistic, that is: in reality, when you pull out the chiki, you do not start the process of detonation of the grenade, but unlock the lever that causes the detonation of the grenade, I fly away from it only when the person releases or throws the grenade, and only then does the detonation process begin. In hl2 this process is well conveyed, unlike hl1

[Shift]

Who the hell knows why they did it, but once you bring back the grenade cooking, you won't want to go back.
Potential exploding is just a risk/reward mechanic, you can speedrun with other explosives jsut fine, and since the grenade is based on a real-life smoke grenade, realism wasn't a consideration (which is what Valve says in every interview about game mechanics, but people can't let go).