For years it seemed that most of the things I knit, the final instructions on the pattern were, “Do not block”. I think that is because the yarns suggested were mostly acrylic. Blocking is nice and most things can benefit from a little blocking, but it depends what you mean by blocking. I don’t suggest ironing or heat treating everything. A lot of projects look fine without blocking of any kind but even they look a little better as some have said after washing and drying, or laying flat to dry. I rarely pin anything out.
As someone said lace needs it, at least in some fibers. I made a cashmere lace scarf once and it looked pretty awful before blocking, but beautiful afterward. I usually just wet block when I do it. Wet, or wash the item and flatten it out, pin it as needed (with the scarf I even used blocking wires).
I have seen even an acrylic baby sweater look a little better after being wet (you can spray too) and flattened and left to dry.
So do it if you want, but don’t feel that you are a failure as a person if you don’t block.