I thought the same thing until I started reading charts, and as I'm in AUD theres no charts available, so I read in sats and I watch BTC price, I use a calculator, its all sorta programmed in back of mind now and I can guesstimate AUD price, or I just confirm at my exchange in fiat, it helps to watch BTC I think, gives me a feel for the market. Sats may be silly but also very relevant, and getting used to decimal points and all that is good practice. Doesn't sound like you are spending BTC or earning it ?
I am only interested in how much my crypto is going up in GBP really but most charts only offer USD. I don't spend BTC no and never have. I spend USD and GBP however.
When I look at my Bicton I am only interested in how much it's worth in money I can spend. I understand the dominance thing but that's what I use Coin Market Cap for.
A coin can go down against Bitcoin but if it's going up in USD do you care? All it means is either BTC is going up or down at a rate faster or slower than said coin.
It's a good way to understand the underlying strength of said coin and how dominant it will be in the long run. But what if another coin becomes the market leader then we will be using something else.
Until I can spend BTC I am not one bit worried how much it goes up or down against it. I am only interested in knowing how much money I have if I cash out!