So, where is this coming from? This is a great group but I sometimes see statements bandied about that are unsubstantiated by evidence. In some cases it almost seems a little crunchier than thou to see how late you can start solids or how fully baby led weaning you can be. There is nothing wrong with purées IMO either.
(Please note I am NOT arguing for solids before about 6 months, or processed infant cereals or overfeeding of solids, or forcing solids on a baby who refuses them.)
ETA: I also keep seeing this babies can't digest grains thing, but find that to also be unsubstantiated when we're talking about babies 6 months or older.