While you are not wrong about these different specialities within the trade, there can still be an effect. Let me illustrate:

Suppose you like bananas but not apples. One day there is an apple disease that kills most of the apple trees leading to a collapse of the apple market. You feel relieved because you don’t eat bananas anyways. But you go to the supermarket and find that not only are the apple shelves empty, the banana shelves are empty too! Why? Well people still gotta eat, and not everyone is as picky as you, they switched to bananas and now the banana market is under supplied too. And it’s not like you can build a banana farm overnight.

Back to electricians, if the salaries of data center electricians increases rapidly, you will find that those electricians who are qualified for both might focus on data centres, straining the supply of residential electricians. Just like with banana orchards, it takes time for new electricians to enter the market, and those will be swayed to the data center specialty first, further straining the residential market.

We can see a real example of this with the price of RAM. RAM manufacturers saw increased demand for data centre RAM so they switched focus to that market and it ended up drying out the consumer side supply, hence the surge in price. And just as with banana plantations and electricians, you can’t start up a RAM fab overnight.