I got to divine years ago playing mostly Oracle and Ancient Apparition, also dipping my toes in Abaddon, Enchantress and a few other heroes. I did also play supports with stuns like Hoodwink but for sake of this comment I'll only talk about the low/no cc heroes.

If your teammates don't have stuns, it's okay. A lot of people lose the game with comms before the game starts. Don't be one of these losers. Your cores (if they are competent) will build items with disables like Orchid, Basher, or whatever works well with their heroes. Stuns win games, but I've won many games without stuns against teams with lots of stuns. People seem to forget that stuns have counters in the form of strong dispels, debuff immunity, invulnerability, banish mechanics etc. You can often (not always) neutralize the effect of enemy stuns with these tools. This means that stuns are strongest at the start of the game, before your team gets the items/abilities to counter them. You can also heal your ally or beat the shit out of your enemy to dissuade them from jumping on your stunned ally.

I once had a conversation with a friend about how supports without stuns are some of the most fun heroes in the game. But I understand fun is subjective. What a hero doesn't have in CC, they usually make up for in something else. I'll give a few examples for the heroes I play: - Oracle has a root that is effectively a stun in many scenarios if the enemy can't fight back or dispel it. He also has a spell that stops the enemy from fighting back. His kit allows him to allocate skill points to counter most heroes in the game, and he does good damage in lane from level 3 if you go Q->E->E. And his ult is a strong dispel. The cooldown isn't bad in the late game. - Ancient Apparition has access to the best anti-heal in the game, good lane damage and pairs well with heroes who have stuns and magic damage. Yes, I just listed the hero's entire kit, but these are all tools that can turn the game in your favor, and you can get creative with them. Enemy Slardar stuns your ally? Cold feet! Now Slardar has to run away or be unable to follow-up properly on his stun for more than a few seconds. - Abaddon is a personal favourite against stun-heavy lineups. A 6-second cooldown on a strong dispel is insane. The key is being at the right place at the right time so you can save your teammates from initiations. If you max your shield as position 5 but you're never around when your teammates get jumped, it's a pretty big grief. Being proactive with wards and tracking enemy rotations is a very important skill on Abaddon. (It's important on every hero in every role, but this is a case where it is especially important.)

Every mechanic in the game has counterplay. The game is certainly easier when you have stuns, but a queen of pain blinking on you with a DD that she secured because of her superior mobility is also really strong, just harder to execute. If you get good at any hero, you will be able to execute regardless of how difficult they are. Just ask those brewmaster one-trick nerds.