You thought about this of course. But I disagree with it.
Someone is 0/3 in lane. You don't want to buff towers because you want other team members to be able to help the other lane sooner.
That's not going to work because the person who snowballed will be pretty strong compared to other lanes. They get first tower and their team has a huge advantage as they can just keep pushing bot turret and force another lane to give up a tower or get rift herald for a free tower. Then they can easily secure baron because it doesn't deal damage - so you just need to keep smite up. You also will automatically win the team fight since most of baron's damage is null.
If you buffed towers - the 0/3 laner would stay in lane longer and might be 0/4 or 0/5 but the enemy laner still gets less gold compared to another tower or a kill from another lane where the kill gold is 300 rather than the measly 250 or 150 they get in their snowballed lane since your ally is feeding.
Ally may be able to scale and still have equal CS while your lanes have enough time to win, force a back, get a good back and roam, make more opportunities, etc. League is all about time.
Towers being weak is supporting snowballing in itself.
Edit: TotalJerk's comment in the comment section is a very good paragraph on some of the issues with towers. I won't post his entire post here as I would like his comment to be upvoted by here's some of it:
> Also, it's actually a common tactic in high elo to NOT take the tower so that you can continue to deny the losing player CS more safely and even bounce the wave back to your side more easily for a freeze. If you take the turret and continue laning you have to put yourself in a position where it is much easier to get ganked.
This portion may seem like it counters my post - but it's also stating towers don't really do much for you if you're getting dived. There's very little risk against good diving champions like Akali, Katarina, Zed, Hecarim.
Edit: Comment section is a bit toxic. Please respect each other and Riot. I understand everyone has feelings on the topic but we aren't going to get to Riot by insulting them or make a good discussion by being over-aggressive to each other.