tank support state

So tell me how tank supports are suppose to be tanks when their starting item is 30hp, adc start item gives 80hp, the final item is 300 hp and no resistances? Ffs tank supports have lost so much hp from items over the years. ? -200 hp, Old ruby sightstone? -500 hp, -400hp, -150 hp and -20 armor.

My adc tells me to stand out front as a tank when the adc has more 100-150 more hp then me early game

Now lastly how the fuck are supports to suppose to have reliable income is removed when items are upgraded?