Maybe? What follows is just my own dumb anecdotes.
For a long time, I sometimes had issues. I'd keep anti-diarrhea pills in stock at home. I kept some in the car. I even had some in blister packs my wallet (they'd get smashed up over time, but they still worked in powdered form and the desperation was very real).
I didn't know why that was a problem, but I definitely knew it was a real problem and that it could erupt at any time, so I treated the symptoms when that was useful to me. Sometimes, those shitty days on the toilet were intense. They'd wreck me, physically and mentally, for far longer than I want to think about.
Eventually, after decades, I noticed a pattern: Milk. Days when I drank milk or ate ice cream were much more likely to be problematic than days when I did not.
But then, I noticed that some other milk products like cheese were usually just fine. And that made sense and fit the pattern well, because the fermentation of cheesemaking reduces lactose very significantly.
And I like milk. So, experimentally, I started buying lactose-free milk. This worked well, but it was expensive and it tastes different. That helped to further define the pattern.
I started buying cheap lactase tablets instead, in bulk. That saved a fair bit of money, tasted good, and it also worked fine. This also reinforced the observed pattern.
Somewhere along the line, I became interested in kefir, so I bought some completely non-mystical mass-produced kefir from the grocery store and drank some.
Kefir treated me fine (yay fermentation). I found that adding a bit of kefir to a glass of milk also worked: That was never problematic at all, even without lactase tablets. (And it let me stretch that delicious, to me, kefir flavor out over a larger volume -- which also saved some money.)
I found that these observations strongly suggested to me that I was lactose-intolerant.
This went on for a long time; several years. Lactase or kefir, with milk, in various amounts -- whenever I felt like it. I thought I was proactively managing my apparent lactose intolerance very effectively. And by observation, I was indeed doing so. Keeping active stock of anti-diarrhea pills always nearby was reduced to kind of a fuzzy memory.
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And then one day, I wanted a nice big ice-cold glass of milk, so I poured myself one. I went to the cabinet in the kitchen, but the lactase bottle was empty. I went to the fridge, and the kefir was gone.
So there I am, with a big glass of milk and nothing to help me digest it.
My health-and-sanitation spidey-sense refuses to let me pour stuff back into containers, and my dread for waste refused to let me pour it down the drain.
So I drank that milk. It was every bit as delicious as I expected.
And I expected (anticipated) the worst, but nothing bad happened. Everything was fine.
One sample isn't a trend, so I had more later. That was fine, too.
Weeks went by, then months. Now years. No issues: Milk goes in, and everything comes out properly.
I can have milk without assistance whenever I want, and that's fine. The previous and clearly-evident pattern that suggested lactose intolerance has become broken.
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So now I don't have lactase tablets in stock anymore. I still drink the least-fancy milk I can get at the grocery store whenever it suits me.
I do enjoy some kefir from time to time (I love the taste of it), but I haven't had any of that for several months now either.
And I'm still fine. I'm doing really well in that area, really.
I'll leave it to the microbiologists to explain the hows and the whys; that's not my field of study. All I know is that this aspect of my life is way, waaaaaaay better than it was.
I'm very deliberately not providing causation or theories here. This is just my story, and I'm sticking to it.
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(Now, someone reading this probably has some questions that are shaped like "Holy hell. Decades? Why didn't you at least go to the doctor or something?"
And that has a simple, dumb-as-bricks, one-word answer: 'Murica.)
