So for me as a long time Dota 2 player, I have been playing the game basically non-stop since the new patch. I wanted to test how universal heroes interacted with the game and how this changes item choices for the heroes in question to get a better feel for them. And the answers left me a bit puzzled but lets break things down a bit shall we.
So the universal effect is basically you gain 0.6 attack per attribute you have. This means that late game you will have slightly more base attack than your contemporaries. Which means universal heroes are designed to scale to a degree. The only issue I find with this idea is that well there is a lot of universal heroes that just simply don't benefit from this effect at all.
Heroes like Venomancer and Timbersaw don't need high base damage anyway and they both build predominantly int items anyway so there is really no need for them to spec into other item types.
And then there is other choices that don't really need attributes much at all in their kits. Snapfire and Magnus who largely scales off attack and only buys specific items for utility purposes to be a better support or engage, but not heroes that particularly scales with their attributes alone, except for maybe a little bit of int to be able to cast more spells but thats about it.
Then there is some characters who I feel scale a bit too well with becoming universal, like say Marci, Broodmother and Lycan. Who both really love Sange and Yasha which is a duel scaling item for them, and items like Bloodthorn which just give so much for so little, yet unlike most int right clicks they aren't so squishy to consider taking it a real trade off. Or Clockwork who can build more items now like butterfly to make themselves more tanky to right click damage and to make close encounters in their cogs especially lethal.
I am not complaining it opens up a lot of avenues of play while leaving most of them unchanged. Because there isn't that many tri-scaling items in the game, very few characters actually benefit from the full brunt of universal's bonus damage and so its more productive to scale only 2 attributes in my experience. Personally what I hope in future happens is that universal can also scale, either their spell damage or mana pool based on their total attributes so that the more caster based members feel a bit less left out but thats my personal opinion.
Source: https://www.reddit.com/r/DotA2/comments/12yx2hl/what_do_you_think_about_universal_heroes/