I replied that it was a bit like me and ice skating. I can't do it - has no one noticed that ice is slippery? When I watch skaters I am awestruck. I think they're all brilliant. If it's the Olympics they're even more brilliant, which is about the limit of my critical facility. I can't even tell the difference between a triple axel or a double, it's all too fast and whizzy.
But if I watched lots of skating I'm fairly sure that I would gradually learn to distinguish one skater from another. (Only fairly sure it has to be admitted. Skating really isn't my thing.) And the more I watched the better I'd get at distinguishing the good from the brilliant, the average from the okay.
Reading is the same. The more you read, the better you become as a reader. And you learn what makes something work, or not work, by osmosis. Hopefully you can then transfer that knowledge to your writing. Now, it may be that you've read so much in the past the knowledge is hard wired into your system and you don't need to read so much now. But I think it's fair to say that most - all? - writers have been at some time heavy duty readers.