This is a question that I've been getting a lot so I thought I'd address it here...
In my opinion, no, but you have to know when and how to use it! In general, I don't like to use blanket statements for anything when it comes to haircare since there are so many variables. So, when I see people avoid things like the plague because someone else does it, it makes me shutter!
If your hair is damaged from heat, coloring, wind, etc., then you could probably benefit from using a low protein conditioner now and again (not necessarily every time) and alternate with a no protein moisturizing conditioner. If your hair is fine, protein can help to give your hair some body. If your hair is normal and not damaged, then every week or two wouldn't hurt. If your hair is thick/coarse and not damaged, you probably won't need to use a conditioner with protein. However, if it has been damaged, you can still benefit from throwing a low-protein conditioner into the rotation.
For me, (3c/4a normal-width, thick density hair that is has been colored), a little protein is a good thing. Now, that means a little protein in the conditioner (like in Curl Theory Moisturizing Hair Conditioner) where there is enough to make my hair glossy and manageable, but not enough to make it hard or stiff. Those are reconstructing conditioners/protein packs for serious damage and I honestly have never had to use those. I alternate a moisturizing conditioner (like Hibiscus & Banana Deep Fix) with the Curl Theory Conditioner on the 3rd day and I am just fine! Love it!
I find it is true that for "normal" unprocessed hair, if you use a conditioner that has protein every day (and the conditioner has a good amount of protein in it) it can build up on the shaft (especially if you don't use shampoo) and lead to dryness/brittleness (in which case you might try shampooing and following with a moisturizing conditioner). But it is good to use a low protein conditioner when you notice that your curls are not as...well...boingy/springy as they used to be and/or have some frizz. You could be lacking a little protein. Try it out and see how you like it! :-)