It's not that anything is wrong with it, it's just completely unnecessary. Babies who are ready for solids don't need purees. Babies who are still nursing or taking a bottle will use milk as their primary source of nutrition for that first year at least so introducing solids is a supplement to that. The old saying goes "Solids under 1 are just for fun."
Solids are to give your baby the experience of getting ready to convert, eventually. We started with half bananas, mushy cooked veggies, shredded meats are great to start with.
So many people are hung up with spooning rice cereal in their baby when it's nutritionally void and is taking up lots of room that milk should be taking up. I've never read the Baby Led Weaning book but you might want to. It may explain the whys better than I am.
Of course we spoon fed things like soup and yogurt but honestly I would hold up the spoon close to their mouths and let them grab it and put it in their mouths. I think much of baby led weaning is not shoving food in their mouths for them. Helping them get a grip on a squishy banana is great but not "feeding" them.
And most commercially prepared foods for babies and toddlers are either purees or junk food like "puffs" or fruit snacks. I did buy rice rusks as a thing for them to work on as a longer-eating treat.
Just watch your baby and once he's at least 6 months, see what you think he's ready for development-wise. Some babies don't get interested in food until 7, 8, 9 months. Mine all went pretty gung ho at 7 months or so.