The article shows interesting points to consider when you buy chickens or are a new chicken owner. But contains a few personal opinions/experiences imho. :
I am surprised about what you claim about bantams: “Most roosters are docile and calm, especially breeds like Brahmas, Leghorns, Silkies, and larger breeds, but you're more likely to end up with a mean rooster when raising bantam breeds like seramas, Old English Game Bantams, and more.

”
And
“CAN I HAVE MULTIPLE ROOSTERS? The answer to that is yes, (except for bantams)”
Where do you have this information from?
I had several bantam cockerels, different breeds, and I had a few very protective but several docile cockerels too.
I can’t keep roosters in spring (when they start to crow loud) but I had several who were 6- 8 months old and their characters definitely showed.
My individual bantam cockerels:
Protective: Dutch, naine de Tournaisis
Friendly: RIR, Sulmtaler, Amrock
+ I rather say protective and not mean. The protective ones just did their job to protect the hens from intruders. And because they are so small, they never hurt me.