I wont dispute the research you've done....if you think magnesium is the savior of your plant then OK....
but when watering a plant when a well is the source of water, then you have to look at possibly its not magnesium.....but salt that is doing the yellowing.
Hopefully you water your plants--including your garden--from a tap off the system--otherwise you are encouraged to speak to a plumber about using instead of salt...potassium..which doesn't affect plants.

A lot of talk has gone into the benefits of epsom salts...especially when dealing with vegetables...notably tomatoes. Epsom salts will bring the red out of a lazy tomato. A lot of people swear by its use usually suggesting their plants are bigger, more bloom, more robust...and so on and so on.....but they don't suggest they grow one plant over here with E.S...and another over here...without it and then have something to compare to.
But as long as they are happy--as long as you are happy, then who's to say different.