If you have a few hundred games under your belt, you may notice a pattern of sorts in games where you either crush the enemy team or get demolished yourself. Among many other things is tower disparity. The idea is that once the enemy team is ahead more than two towers, things start to get rough and the snowball begins.
This is because of many reasons. To name a few would be like:
B) Loss of map control which comes with losing tower
C) Enemies can move around more now, doing shit, making games difficult
While all those points are related in some ways, I guess C matters the most. If you are behind towers, you are still sort of stuck on early game phase (laning) while the enemy is transitioning into mid game phase (going around, doing shit, starts moving from one objective to another, often towers). Team could then starts reacting too much, sinking a lot of gold into TPs when they're already behind in gold, and all sorts of bad things tend to happen.
So yeah, try not to get behind in towers.
But my carry needs to farm. How can he farm if you raze towers early?
This is really a non-issue if your carry player knows how to play. He'll find ways to farm, as long as the supports give him room to. Razing tower in safelane could be a good thing for carry too, since it gives opponents less entrance to a gank. What's important is deterring the enemy from trying to win in 30min.
Textbook dota is somewhere along the lines of six towers by 20min, rosh, then rax, which is followed by continued pressure into gg. If you lose to this. It's not so much being outplayed mechanically. You are simply being outplayed by strategy and draft. This is arguably worse because you didn't even really get to play the game.
How to keep up in towers (early game)
If you have a chance to chip the tower, even if it's one autoattack or two, do it. You want the tower to be reasonably damaged so when you do want to push it down, it comes down with ease. It's an integral part of proper lane control.
Here's a scenario that happens far too often:
In a standard 113 vs. 311 matchup, dire is pushing top (their safelane) aggressively while radiant bot retains a passive game by freezing the lane and just farming it. Dire bot tower remains untouched.
Several outcome can be expected of this. If it's early enough, dire can actually go for the second tower without being contested too much because the fact that they got the first tower implies that they have a powerful pushing lineup, and it's so early that most antipush heroes don't have enough levels for their nukes to be potent. With the abundance of gold and space they created, the supports will move around the map making life hell for radiant while dire carry farms top.
Meanwhile, bot lane is still doing dickall static farming like it's 2006. Their farmville equilibrium gets disturbed due to do-shitness of dire side (because they really don't have anything better to do). Radiant bot laners are confused, which generally leads to upset emotions and the eventual blaming.
Sound familiar? It's just about every game in matchmaking. Truth is, the measle amount of gold that one player is getting per cs in bot lane isn't going to compensate for what just happened at top, and what is about to happen at other lanes.
And this goes back to the idea of equalizing towers again. You should look to chip the towers on siege waves, all the while deterring the enemy suicide laner from getting experience. You do this by zoning the enemy hero out of his tower, and kill him if he tries to get experience. Proper zoning under tower can be a difficult thing to execute properly, so, that may take some practise.
Even if the enemy aren't doing what I said above, you should still try and chip the tower if the opportunity allows. It just gives you more control over your lane, and over the game.
I think that about sums up what I want to talk about towers in this article. Cheers.