The following might not interest old-timers so much; it's mainly for anyone who's newer to this hobby.
X/Y has its uses, and can sound good sometimes. But a lot of people use microphones with pickup patterns that are too broad (especially at low frequencies), and they don't set up a wide enough angle between the microphones. This isn't their fault; there are lots of really ignorant or overly generalized suggestions "out there" about how to set up microphones for stereo recording. Plus the design of some recorders and even stereo microphones with X/Y cardioids at a fixed angle of 90 degrees suggests that that's some ideal, scientifically chosen arrangement, when in fact it sucks big time for music recording at medium distance.
[1] Cardioid isn't a narrow pickup pattern! When you're recording with only two microphones (or when your main stereo feed is coming from one "main pair"), the overlap between the microphones goes right to the center of your stereo image in playback, i.e. it's like using a mono main setup with much smaller contributions from separate left and right microphones. And even if you put two cardioids completely back to back (i.e. 180 degrees) so that they have the maximum amount of separateness for an X/Y pair, literally half the output of each microphone will be exactly the same as each other. That's what a cardioid pattern means: 50% pressure response (= inherently omnidirectional), 50% pressure gradient/velocity response. This removes the vividness of the stereo image as well as fun possibilities at low frequencies.
As a result the pickup angle for X/Y cardioids at 90 degrees is hopelessly wide. It might be a fine setup for recording round-table business meetings (the application which most of those recorders are mainly sold for), but for a relatively narrow angular range of sound sources coming from some distance away, I agree--friends don't let friends use such a setup.
[2] Especially people who are new to this hobby don't understand that the wider you angle your mikes apart, the more specific (i.e. differentiated) the localization in the eventual playback will be. Intuitively it seems as if a narrower mike arrangement will lead to more precise "focus". And with narrower mike setups, yes, you will pick up somewhat more of the direct sound and less of the diffuse (reverberant) sound, which is important. But for most "semi-distant" music recording, the default angle for cardioids should be more like 120 degrees than 90; you might even increase that angle sometimes, depending on conditions and taste. In any case 90 degrees isn't some kind of magic number where cardioids (or even super- or hypercardioids) are concerned.
[3] On top of that, many cardioid microphones are cardioid only in the midrange; their patterns get broader (i.e. even MORE like omni) at low frequencies (just where you need that NOT to happen), and narrower at high frequencies. The worst offenders are large, dual-diaphragm cardioids (including the cardioid setting of most large-diaphragm stereo microphones). This is why I rebel against the social pressure here to respect some people's choice of "LDCs" as if that were simply one equally valid aesthetic preference among others. If so, it's only the visual and historical aspect and not the auditory aesthetic that I can honestly respect.
Coincident and closely-spaced stereo recording makes very specific demands on a pair of microphones; consistent polar (directional) patterns need to be maintained throughout the frequency range, otherwise this trick of the brain that we call stereo imaging doesn't work nearly as well. And large-diaphragm microphones (especially dual-diaphragm microphones, which most large-diaphragm cardioids are) physically can't meet those requirements. So please don't get distracted by looks, in-group feelings of personal coolness, or studio traditions for spot/solo miking where the requirements are quite different.
[4] The reasons for considering supercardioids instead of cardioids for stereo recording has little to do with filtering out crowd sounds, and much more to do with increasing the difference between what the two microphones in the pair are each picking up at any given moment (again, working with the brain to make the stereo trick work, rather than against it). Yes, they are also a bit "drier and clearer" sounding, but this depends a lot on the room and the distance as well as the microphones. Also, if they're well made, they'll still have a good directional pattern even where their frequency response rolls off, so any deficiency in low-frequency response (which a lot of them have, because they were designed primarily for speech pickup in reverberant/noisy environments) can be compensated with EQ. It's not cheating; it's undoing a design feature that was built into mikes made for applications different from our own.