I love reading, read loads, but often read what is considered trash or not very useful stuff. Love a sports romance, love some fantasy. Absolutely cannot stomach a classic. Hate reading to analyse themes or whatever. Just want to enjoy my book and move on with my day.
But I know for a fact that even though I do not read highbrow literature, or very much non-fiction, reading has 100% improved my vocabulary and general comprehension skills. I have mispronounced a lot of words in my lifetime because of only having seen them written down, but I wouldn't have otherwise known those words or how to use them if I hadn't found them in books.
General comprehension skills are massively declining. You only have to look at an internet comment section to see people are missing the point of a lot of content they are viewing online. Reading helps with parsing information, analysing, looking for context clues, literally reading between the lines, in a way that I don't think other media can replicate like for like.
That said, you can definitely be a smart, intelligent person without reading, it's just that reading on top of that would contribute even more.