Is STSF slowed or mitigated at all by being blind/dirted?

Pretty sure if you can't see someone, you can't observe them to charge up STSF.

Pretty sure that isn't correct, and there are log snippets on qhcf showing otherwise, but I don't have logs to search myself...

Seizing upon a flaw in your tactics, Nazarates kicks dirt toward your eyes!
You can't see a thing!
Someone's kicked dirt scratches you.
You sure are BLEEDING!
You continue to observe someone, and revel in how you may predict its every maneuver.
Your searing light MANGLES someone!
Someone parries your punch.
Someone dodges your punch.
The attempt failed.
Someone is convulsing on the ground.

...this message is simply stating that the counter is still active.

But I think I'm wrong. I thought I remembered Daevryn telling me that being blind stopped STSF, but maybe it only hinders it?

I'm fairly sure I remember Nep saying something similar in a post once, damned if I can find it though. Maybe it's supposed to and it's a bug? :P

I'm like 99% certain that Daevryn's said being blind hinders STSF buildup.

"For example, studying your opponents' fighting style is a lot harder if you can't see."

http://forums.carrionfields.com/dc/dcboard.php?az=show_mesg&forum=6&topic_id=19929&mesg_id=19930&page=

Otherwise an explanation here could be that once it's charged being blind doesn't do anything and the echo just states that, even though the it doesn't make sense.