My reasoning for alkalinity over salinity and temp is simple. Everyone starting up a tank be it an experience reefer or a newbie is measuring salinity when they setup the tank. I'd guess 99% are checking temp too and 99.9% should fall into some sort of acceptable range even if slightly outside the recommended level say 70-86. Unless you are in an unheated cabin or a non air conditioned tropical apartment temperature should be uncomfortable for you just as quickly as for your reef.
Heaters do explode and fail, chillers although less common today are still in use a lot and can fail too but you are much more likely to notice this vs alkalinity either dropping or spiking unless you are using a calcium reactor. Additionally if you started with 1.026 salinity or something close to that it should in theory take a long time for that to leave the range of acceptable assuming you are at least measuring your freshly mixed saltwater even if you aren't checking your water change water with a calibrated refractometer or salinity probe each and every time.
If you are doing nothing, using a dosing pump or even manually dosing alk is going to swing one way or the other unless you are monitoring it. With the exception of the seasonal changes your house and tank temperature shouldn't swing too much nor should your salinity but alkalinity requirements will change based on how many corals you have.
Heaters do explode and fail, chillers although less common today are still in use a lot and can fail too but you are much more likely to notice this vs alkalinity either dropping or spiking unless you are using a calcium reactor. Additionally if you started with 1.026 salinity or something close to that it should in theory take a long time for that to leave the range of acceptable assuming you are at least measuring your freshly mixed saltwater even if you aren't checking your water change water with a calibrated refractometer or salinity probe each and every time.
If you are doing nothing, using a dosing pump or even manually dosing alk is going to swing one way or the other unless you are monitoring it. With the exception of the seasonal changes your house and tank temperature shouldn't swing too much nor should your salinity but alkalinity requirements will change based on how many corals you have.