Has the purpose of the assassin role been skewed over the years?

Let me explain before you guys come in with your opinions. From the earlier seasons of league. More specifically season 3 and 4. Assassins have always been champions that poke you down with their abilities and then when they're comfortable enough. They come in with the rest and take out the squishier targets. Those that managed to get ahead were most effective in taking out squishy targets and relied less on poke. In my opinion old was the shining example of come in after squishy targets for cleanup. Then when she got a few kills ahead, she was able to pretty much 1v1 any squishy. Now instead you have champions like who have an incredible gold efficient item because that item is almost teed to get the target with little effort on the assassins part.