Just my opinion, but I think most people who don't believe in bonds to smooth things out are most likely right on the cusp of having their numbers work to support their retirement using the 4% rule. Math and history dictates that these people are correct in their plan and will be totally fine.
Now imagine for a minute that you had your 100% equity stash (or damn close), and lets just you had a windfall of an amount great enough that if invested in boring old bonds would pay for your "fatfire" dream lifestyle forever including inflation. You can still keep your original stash 100% equities and never need to touch it...it just keeps growing, but you never have to even blink or consider money ever again.
Now you are a true mustacian, so you don't believe in lifestyle inflation, you aren't greedy, and you already know what lifestyle will make you the happiest and have planned for that. What reason other than 1) You really undersold your "fatfire" number in the first place to make yourself feel better, but it was really much higher 2) Charitable endeavors 2) Creating generational wealth, admittedly I don't believe in 4) Ego associated with having your name on a building, would their be to take on the added risk?
I know many people who would be considered very wealthy in the $10M to $200M range and not one of them thinks like this. I'm just saying that there are going to be some people on this forum who blow way by their # years down the road, and I'm guessing their tune will change when instead of having 33X their annual burn they have 100X or more. Anyway, just food for thought, that might be a reason to not totally poop on the idea of owning a bond portfolio.