I never see threads arguing for 95% stock portfolios. Nor 105% portfolios. It’s always 100%. I’m not sure what the fascination with that round number is other than it is round.
The primary reason people cite for 100% stock portfolios is because in the long-run, at least in the United States, a 100% stock portfolio has had higher returns than a portfolio that contained any percentage of bonds.
This idea that stocks always outperform bonds over 20+ year periods really only applies to the US and the comparative advantages the US has enjoyed in the past were significantly higher.
When setting up a portfolio in “normal times” lots of stocks make logical sense. But staying the course in a bear market is not a logical experience. It is a profoundly emotional one.