Fighters are to be front line, they do damage to protect the adc and the apc. They punish you for walking into them. Most tanks do not have cc, or reliable cc, that is for the mages, and some adc's. Leona has a stun, thresh a hook, knock back, but that doesn't stop highly mobile champs. Your complain here again says you don't understand how a team fight works. I bet your the adc that yells into the team "don't focus tanks" or the fighter that doesn't front line and tries to chase the adc instead of protecting yours because "don't focus tanks". The jg is usually the one to try to get to back line, or expose the adc/apc, but if they can't if you ever watch good, pro, matches they do kill the tanks a lot first, because they take who they can get to. They let those with mobility, usually Assassins get to back line on adc/apc of course that is the Assassin, or highly mobile champs job.
Problem is you want to be the tanky Garen/Darius/Morde, I don't care pick your top laner here, but you don't want any downside and no one to be able to counter you. Why shouldn't you ever be able to be cc'd ?? Sometimes it is the job of the Mage and ADC to peel for themselves if they have to. YOU have to know what your teams strength and weaknesses are. If you have a Garen top, with a twitch jg, and a sena support, and an ahri mid, and a Jhin adc. If your JHIN, SENA, AHRI, TWITCH you have little peel with a Garen as he has a silence and damage as his peel. So yeah you will be peeling for yourself. SOMETIMES YOU HAVE TO.
Also you are comparing Solo Que, or Normals to what the game design for play actually is. This IS a team game where when 5 people work as intended, the mechanics are totally different. Hard to calls something not fair or broke, when game is not being played as intended.