Greetings.

Seen often that after dough is left to rise for a long time, is purposedly deflated and put again to a second rise.  Why destroying the first rise ?

I did this a couple of hours ago for some barm cakes. The dough rises as it proofs and air bubbles form. You want to knock that down/punch it down/fold it in on itself to break those bubbles up and get the yeast back together with the sugars and moisture and starches to form up a better bond/grain/crumb. It also improves the flavor as it brings the ingredients back together to complete their chemistry.

For rustic soup breads where lots of air bubbles are a plus, I never knock the air out, just mostly on sandwich breads where I want an even, tight crumb.

I don't kneed at all these days.I  just incorporate  all the flour,let it rise  and then turn it out into the tin to rise before putting  it in oven.

Not as good as from a good baker's but easy enough and perfect (normally)  when fresh.