I disagree that you can cover up artifacts, especially electronic based ones. You can pile other distortions on top of the existing distortions and you usually end up with something just as bad or even worse than what you started with. A good example was some early chinese DACs that wanted to cash in on being "tube" DACs. They would simply slap a cathode follower stage on the end of a bog standard SS stage, usually with multiple opamps. The result was some tube syrup (from a poorly designed tube stage) added onto the synthetic sounding opamp output stage.
This is what a lot of people try to do as well with a tube preamp and a SS amp. They think the tube stage will add some "sweetness " to their analytical sounding SS amp. What you really get typically is something of the worst of both worlds. That is not to say that two really good stages that are different tech can't be designed to work well together and complement each other, but unless designed together you are playing hit and miss. Far better to have a pre and amp that are natural in their lack of audible artifacts than one with flaws that you are trying to compensate for with other, opposite flaws.
Define artifact please... Everyone is slanging that term around like it actually applies. Unless a stereo is broken then anything you hear is on the recording (barring uncleaned LPs). Literally every bit of it. The problem is stereos cause aberrations to the music, so something benign suddenly sounds totally out of place, or all wrong. They don’t add noises of their own unless broken. Even a poorly setup cartridge ringing like crazy, is still changing the sound of the record, not just throwing a new noise into the mix because it only rings when it is excited by certain frequencies. At most I’d say some people hate there being a trace of the studio - the irony being if you remove it the music usually sounds dull.
As far as covering up, I have no idea how you think that’s not possible. Given that what audiophiles often call distortions in the music isn’t actual distortion, it’s really not appropriate to say you can’t cover up something with distortion or consistent aberration. I would call kitty litter boxes a consistent aberration. And also it seems like a fair amount of equipment would prefer to limit the dynamic headroom otherwise you notice a glaring flaw when it can’t deliver at some peak moment.
I’d even go as far to say people like consistent aberrations enough that there are plenty that make it into the “natural” camp, and ultimately help to reduce undesirable sound that’s included with the music, or simply homogenize it so you don’t detect anything. It may sound right, but only conveniently coincidentally discovered to assist in avoid a flaw from the music production process.
The major mistake is believing everything good to the ears is derived from objectively good for measurements and ethos of the stereo equipment. It just is not so. Natural or HiFi, it isn’t a line in the sand for what is objectively better with the equipment in any way. One just sounds better to one person but maybe not another. And it will always be that way until some out of this world technology radically changes everything we to be true about the process of recording and delivering to a medium.
Think about it, do you consider floppy-ass boxes used with vintage speakers to be objectively good? No, no one actually thinks that. But those wise enough to listen might be using $130k Lamm amps on a garage sale find, perfectly content. So maybe what you think you know isn’t true how you think it is, or maybe certain aberrations that are consistent in the right way are simply more pleasurable. Those floppy box speakers could measure well or poor, either way they offend every inkling every audio mind has about what’s “better”. It’s not a surprise since so few audiophiles understand some common things when it boils down to actual physics or electronics - and it’s not necessary anyways but somehow forums are full of people going in circles about everything.