I can see where you're coming from with your OP, totally.
Both of my chidren have taken to solids with extreme enthusiasm, moving from baby porridge/purees in the course of a week or so and then straight onto roast dinners, bread cheese and salad, spag bol, whatever we're eating, and in hug quantities.
With DD1 I did wonder whether I was "supposed" to restrict her solids in order to force her to take more milk but (not having anxiety on the issue - that must be very hard for you) I decided that it would be silly to stop giving food that a baby was eating with enjoyment and gusto.
I can't remember how many feeds DD1 had but DD2 dropped to 2 feeds a day at about 9 months and has been on 1 feed a day since 10 months (BF).
All children are different and the guidelines are tailored to catch one end of teh scale. There will be lots of babies who don't take to solids that well, or do it later, or don't like or are allergic to animal dairy products, or turn their noses up at anything except pureed carrot, or have small appetites, or are sick a lot, or whose parents don't give them very nutritious foods. For all of those babies, the guidelines of "loads of BM or formula up to 12 months" will be a huge help and will mean that the babies get all the nutrition they need for a reasonable time ie the first year.
Be led by your baby. Everything will be fine
(Forgot to mention that DD1 is v healthy and strapping and healthy etc at nearly 3 and DD2 (just turned 1) seems very cheerful too!)