Why doesn't tool strip nclude slider for masking tool as shown on a number of videos detailing how to use masking?
Give us an example of the URL where you see this "slider for masking tool"
When the local adjustments sliders are collapsed, you instead see just a menu to select a local adjustment preset, and an Amount slider. The latter increases / reduces the 'strength' of all the hidden sliders (while keeping their proportional relations to each other).
Here is a video of what richardplondon is talking about: You see the Amount slider only when the mask options are collapsed.
Are you seeing something like this?
Yes, that is what it looks like.