Exactly, which is why most manufacturers don't use them and always make excuses about their performance not being as good. If you choose the correct transformer, especially in to a good valve phono stage you can get excellent results, which cuts out a lot of passive and active circuitry in the signal path. It is also well known that with a good SUT you get a musical coherence to the sound that is very hard to beat. Another advantage is that a SUT offers protection to the cartridge as it AC couples the cartridge from any active electronics, preventing any DC from potentially damaging the cartridge coils. I have used internal and more recently external SUT's in all of my
TRON phono stages built over the last 25 years. I wouldn't use anything else...