I don't know about ISXP's but I certainly have ran across poor communicators, as a matter of fact I just ran into one today...
i know a ISFP. I have to strangle him to make him talk. arghhhhh
he starts telling you about something. about 5 words later he just stops. then i have to fill in the blanks.
a few years back he told me that he saw this girl at a lecture. well that's it. i had to finish the rest
He - (Enthusiastically) i saw a girl
I - yeah is she cute?
He - yes, but.........
I - but what?
He- she is, you know, she is............... she went
I - (PISSED OFF) she WHAT???????
He -i was.... when she got.....
I -(EXTREMELY ANNOYED) you were what????? about to squeeze her butt???
He - Noooooooooooooooooooooo. i went..... then .... the lecturer
I -ohhhh you went to talk to her?
He -YESSSSS!!!
I - but then the lecturer came???
He -yes, yes, yes
I - so you couldn't talk to her?
He -yes.. and she was wearing green and you know, you know.... and ... you
I - (completely lost and infuriated) what the???
He - stares at me and smiles
I -ohhh you were gonna comment about what she was wearing because it was beautiful?.
but when you were going to say hi, the lecturer came so you went and sat?
after the lecture she quickly left, so you couldn't talk to her?
He - happily nods as if he nailed the girl.
3 years later he still hasn't spoken to her.
i never get annoyed. but pray i do when i talk to a ISFP. or atleast the guy i know.
Ps: we have been friends for about 5 years.
so yes. the answer to your question is yes.