That's so true... and just like every body is different, so is each infection. There might be a group of the same people with the same symptoms that respond to the same therapy... for some people, curing an ailment may be just as simple as taking a pill or supplementing for something that's missing... then it corrects itself. Others may have underlying conditions that they have no clue about, so they can supplement all they want and nothing helps because you can't fix the root of a problem until you KNOW what the root even IS. The immune system might be held up supressing an HPV infection or a dental infection.. or something someone has and doesnt know about... so the candida is left to grow out of control. Some problems or underlying issues are more than the immune system or the body can deal with on its own... but some people will never find out by just going to the doctor because as we all know, their testing methods are in sufficient.

Editing to add the group of people I forgot about. I would be included in this group - the ones who think that simple things aren't enough to fix their problems, so they don't even try.
I bit the bullet and tried eventually and was very surprised by the outcome. The vitamin c and d3 + msm supplements wiped out an enormous amount of stuff that nothing else would touch. You really don't know unless you try it for a while and if it doesnt help, then there's a missing factor. As for candida overgrowth, some have it so bad that it needs to be hit from different angles.