I think you are confusing stern advice over aggression. Times are changing and people are easier offended, but I simply speak the facts with no sugar coating. It is mostly newbs who butcher plants, or ill informed long term growers. If that sounds aggressive then I can't really put it any lighter, sorry.
There are some more experienced growers who defoliate and still yield well, but the thing is, they are simply removing a low enough amount as to not interfere with end yield, or at-least not noticeably enough. They then simply stroke their own ego and pass it off as being ''skilled defoliation''.. and some newb growers see the yield and get sucked into the whole plant butchering process.
Getting consistent 1gpw of mature bud isn't that difficult with the right strain, not allot of effort outside basic plant/environment understanding, like temp range and not feeding toxic amounts of P. No full plant defoliation was used. Getting to 1.3gpw of mature bud takes a little more understanding and decent environment control, still, no full plant defoliation was used. Reaching 1.5 is taking a lot more understanding of actual par values at canopy (light meter) vpd, ppm adjustments to match along with a potential need for co2 and the realisation that open space light loss starts to become more detrimental. According to defoliators, good yield is as simple as removing all of the leaves that utilise everything I have just mentioned.. yet when you ask a heavy defoliator how much the technique increased yield they say ''well I can't say for sure''.
And that there is it... I can tell you for sure what gets you from a 0.5gpw newb 1.3. This isn't to show off, 1.3 isn't that much in the grand scheme of things.. but that is well over 100% yield increase with not a single plant defoliated, while I can give anybody solid advice on how to do the same. go ask a defoliator to do that, they can't.