I love this subject.
The biggest issue with alkaline diets are weeding out the foods, acidic foods like lemons are actually alkaline once reaching the body. This is also the reason milk can be worse for bones not better, when we drink milk or cheese these create an acidic nature in out body, to equalize the oh the body draws out nutrients including calcium from its stores in the bones. This can offset the calcium in the milk. I hate seeing dr say drink more milk, dark greens and other sources of calcium that are alkaline are more ideal. That said a good balance diet won't off set the calcium as long as you have enough alkaline foods in the diet.
It will not change your ph balance permantly or your base line but it helps keep your body in a more stable state through the day with less fluctuation which means less nutrients are lost. Things like cancer are said to develop and thrive in a anaerobic state, an acid environment provides this, one of the suggestions is that by keeping the body at a level state we can significantly reduce or dominate these growths.
You can go over board and develop alkalosis from what I have seen it is best to has a balance of 80:20 if you are trying to come off a more acidic diet and a ratio of 60:40 alkaline:acid is sufficient for maintains the level. That's just from reading.
The hardest part is understanding which food do what.
I also like the ideal at the moment I am developing a diet that using a very good ratio of macros mixed with ideal ratios of mono and poly fats and withing poly a good ratio of omega fats.
My next steep is getting it to a ideal alkaline and acidic ratio.
Don't bother with ionizers thy can actually increase or magnify the metals in the water.
Also the reason people are not onto it is the same reason we have health issues and food producers can get away with pilling crap in our food. Because people don't bother to learn, its not something taught in school. (I think food should be mandatory for every year).
Most people know about basics like salt fat protien and carb. But they don't understand the internal things hence all these fad diets, they play havic on the lack of knowledge) things like ph balance or omega ratios it's just too in depth for most and without diving into it or being suggested it earlier it's not known.
Another issue is ease, from what I have seen most grains and all meats are acidic, grains are hard.
I have only read every on these diets on the Internet so don't take my words as 100% it's just my opinion and understanding from research.
On phone so sorry for some spelling issues.