Again, if one wants to trade successfully, one needs to know SD Levels. The drawing is not really complete as I use Xard's monthly fractal indicator for convenience.
But here an example:

US30 traded in 2015 and 2016 up to the what people usually call Resistance Level of approx.18174 (using the value of the Monthly Fractal SR line) but ran out of demand (buyers) every time. Now why would a trader not to pay attention to this fact.
At 09/11/2016 the bias finally turned to the upside as obviously tons of money pushed it through that level and more buyers jumped in. Since then it just kept going.

When the US30 dropped like a big rock in 2020, where did it stop........18174......Now a Support level. Drawn in 2016, this level has been on the charts ever since.
You may of course choose to simply ignore SD Levels and keep wondering why price action turns at certain levels, crediting this fact to a Dot appearing. Till your indicators tell you that the tide may be turning, professional traders are already deep in the money. They only way we as poor retail traders may know what the banks are doing, is paying attention to those levels. We don't have the data about location of orders and volumes as they do.