So if you've had 30+ games where you dodged, presumably there were equally as many games (technically there should have been 125% as many since you're one of the 5 on your team) where the autofilled troll player was on the enemy team.
Given that you've not one single time of 30+ seen an ally dodge for this, again it seems fairly unlikely that any enemies would dodge. Your 30x4=120 allies gave 0 dodges. Being extremely generous let's say your enemies have a 5% dodge rate on trolls. Ignoring that multiple could dodge at once (reducing total games dodged) that's 25% of enemy troll games dodged, meaning 75% are played.
Meaning you've sacrificed 90LP to not play 30 games with an ally autofilled who's trolling.
You've played 75% x 30 games ~= 22 games against an enemy team with an autofill who's trolling in champion select to hold hostage (he probably tries once he gets in game, but that's beside the point).
You're consciously making the choice that you think you're going to get at least a 13-9 record in those 22 games then (i.e. +4 wins > 90LP). If you don't think the autofill troll makes that big of a difference then you shouldn't be dodging. If you do think he does, then dodging is smart and you're gaining more free wins (whether you realize it or not) than you're paying in 3 LP dodges. That's the entire point of the system. I agree entirely that it's ridiculous in promo-series (and just stupid that oh sure I get guaranteed autofill protection but 3 of my allies can be autofilled for my promo game...) but beyond that it seems to be doing what it should.
Autofill trolls (and all other trolls) should simply be banned - but people seem to favor the idea of reform (even after 4th or later offenses) so there's no sense going that way.