Studio recording mics in general are not flat like measurement mics. They are selected for the coloration they impose on a sound source. It's rare to even see published FR curves for them, and generally they're curve-smoothed and averaged over hundreds of mics; so the data is rather useless.
Yes, I'd have to disagree with this last part too. I have a total of five mics, currently:
Beyer M500 (ribbon—hypercardioid): Bought used from a coworker at Oberheim in 1982. Came with a pen plot. I just did a search, and see mic info with a scanned response plot that's extremely close to mine, and this does not appear to be overly smoothed (
BEYERDYNAMIC M500).
AKG C414B-ULS (LDC—multi-pattern): Bought new in earlier '90s, comes with individual plots at all four pattern settings. I've pulled up a pdf off the AKG's site in the past couple of years, 30 years after the fact—again, my individual plots match closely.
Soyuz 017 FET (LDC—cardioid only): Bought new two years ago. It came with an individual pen plot, not overly smoothed. It looked nothing like the published plot of their website. The mic sounded like my plot, not like theirs. It sounded great, but it made me wonder if if it was supposed to sound the way it did, or different (and it's hand-made). After showing them, they agreed they had the wrong plot, which they said was from a different test company years ago. They put up a new plot that looks very much like mine. (Scroll to the bottom here:
Soyuz 017).
The other two don't count (one was a cheapie LCD that I bought and replaced the components, the other is an SM7B, I don't think it came with a plot). It think you're only getting individual plots with higher prices mics, but I don't know from manufacturer to manufacturer. Things have changed a lot since when I bought the AKG, and the price of entry for an LDC was $1k-ish. Now you can get $50 LDCs, and there are huge number of choices under $1k.