It's more of a combination of towers being the same and in fact have become weaker. Well, everything else has been power creeped over the years. All classes in this game have items that grant health or some form of defense but bot lane crit marksmen have no way to get reasonable defense without being screwed over completely due to awkward build paths or if they do decide to get something like hexdrinker or chain vest it delays their powerspike in a meta where the average plat game ends around 25 minutes. All other classes in the game can at least afford to get some defensive itemization due to the fact that most classes core itemization have really good build paths. There are a couple ways to fix it but 1 requires just nerfing the damage of everything down to a more reasonable level (Trinity force, duskblade, electrocute, summon aery, scrotch, grasp of the udying et ceteria), another is make the crit marksmen buildpath as smooth as everyone else's core itemization, or just add defensive stats to crit itemization so marksmen can survive long enough to deal damage. An example of adding crit defensive itemization would be like infinity edge now grants (5 armor and mr to 20 armor/mr) Based on 0% to 100% crit chance. Another example would be a crit item with an active that knockback a single target an x amount of distance but has no passive. Basically the 2nd option is the best case and the easiest to do without needing to buff the living heck out of crit marksmen.
