[alancalverd (OP)]

If you delete the word "existential" from a sentence, does it alter the meaning?

Likewise this month's buzzword "performative".

Does the word "celebrity" mean anything more than "someone who has no function in your life"?

Is there any kind of experience that is not a "lived" experience?

[Bored chemist]

I remember when someone was a celebrity if (broadly) they were celebrated...

[Eternal Student]

If you delete the word "existential" from a sentence, does it alter the meaning?

   Yes.   Not all crises are existential crises.

Is there any kind of experience that is not a "lived" experience?

  A vicarious experience.

Hmm....  I'm really not sure you wanted these questions answered.  This is a why? and a general moan about language use isn't it?  Well, let's spend a moment looking at it then:

     A specialist in any field needs some specialist lexicon (vocabulary) they can use.   After all, it's not clear what knowledge is and where it resides.   Knowledge is probably not located in the individual but rather in the wider society and made accessible only through the use of language.   Thus, I can suggest that one loudspeaker might be a better match for your amplifier than some other loudspeaker due to their different impedance when plotted against applied frequency - and that conveys meaning to you and the required knowledge for the problem is made accessible. 
   You can also do much the opposite.   Force a reader to engage with what you've written by adding something they will have to decode or analyse to make sense of the information.  It's extremely effective when you emphasise something they will have to do:   "They're right about these speakers being more active.  You'll really be included in the performance with these.  Does your graphic equaliser have sliders or knobs?"

Best Wishes.

[alancalverd (OP)]

Can you describe a nonexistential crisis for my enlightenment? My guess is that you might describe and plan for a hypothetical crisis, but "existential" still adds nothing.

Would a vicarious experience be what I call a "report"?

Your examples of technical lexicon certainly parallel Shannon's information theory: the receiver always has a choice of predetermined interpretations, so you don't need to transmit all the data, just enough  to address the compartment in which it is stored. The induction talk for student nurses used to include "in the next three years you will learn to understand and act on  3000 new words."

[Bored chemist]

Can you describe a nonexistential crisis for my enlightenment?

For the fish in my tank, a failure of the air pump is an existential crisis. It threatens their existence.
For me the rise in fuel costs is a crisis, but it won't kill me.
It is not an existential crisis.

[Zer0]

If you delete the word "existential" from a sentence, does it alter the meaning?
Existential Angst/Crises.

Likewise this month's buzzword "performative".

Does the word "celebrity" mean anything more than "someone who has no function in your life"?
Role Models.

Is there any kind of experience that is not a "lived" experience?
Forgotten Dreams.

(by the way, Why do You keep sounding more & more Philosophical to Me lately?)