'Absolutely'

The current overuse of "absolutely" potentially eroding the sincerity of the speaker would, I think, depend on who the speaker is, and also perhaps the context.
It's interesting that you differentiate between the word's current "related" meaning and its "original" meaning. Could you, Tdol, please explain this differentiation? If you mean that the vogue has changed in a looser, almost slangy way, then I don't think this is new, i.e.
"Do you like my purple hair colour?"
"Absolutely!"
Perhaps this is not what you meant though:-)

I din't mean that, but it is thrown about in current political discourse. I have heard 'absolutely voted'- how do you partially vote? Here, the use is clearly wrong, but the speaker wishes to emphasise the strength of their belief. It has become a marker for sincerity detached from it's original meaning, IMO. ;-)

I can’t believe that I am the first person to respond to the fact that “absolutely’ has become one of the most used words ever. 99% of people don’t realize this due to the fact that no one has mentionred this to them. For those who have read this will now become aware of this fact and you too will soon go looney over its use.

I have instructed my wife to put
‘ABSOLUTELY’ on my tombstone.

mr.bill