Huh, well, bizarre branding then!
At their HQ, they gave out a 'fanatical support' award which was a straightjacket, with some tribal backstory related to being 'so fanatical that you're insane'.
- Former Racker
Branding your support 'excessive' or 'single-minded' would also be bizarre.
Fanaticism is typically taken with religious or political connotations, and derogatorily.
Cambridge [0] says:
> [informal] extremely interested in something, to a degree that someone [sic] people find unreasonable
> [disapproving] holding extreme beliefs that may lead to unreasonable or violent behaviour: a fanatical group that has threatened to assassinate doctors
Oxford [1] says:
> A person filled with excessive and single-minded zeal, especially for an extreme religious or political cause: 'religious fanatics'
> ... originally described behaviour that might result from possession by a god or demon ... (Oxford [1])
(Italics mine.)
[0] - http://dictionary.cambridge.org/dictionary/english/fanatical
Add '~atic' to any of those and it's sounds much more extreme; something to disapprove of.
I quoted Cambridge online dictionary above as defining it as disapproving, the same dictionary defines 'fan' exactly as you use it, and does not give 'fanatic' as a synonym.
Of course it originates as an abbreviation, but the usual usage is very different.
I have at least backed up my surprise at the use with two different dictionary citations, so it can't be that strange of a view.