Reply all has been around for a good while. It’s a valid feature but misuse has prompted those in big business to advise against using it.
And they’re right; you don’t hit reply all to ask the sender a question unrelated to the other 22 team members. Nor do you use reply all as a way to send a joke or to have a conversation with someone the other 30 people don’t want to hear about.
However, in small business, which means small recipient list, it’s a best practice – still, when it’s used correctly.
If the content is relevant to the 1-3 people in the cc list, by all means, include them. I can’t tell you how many times I’ve had to reply to someone informing them to keep the other person in the cc list because they needed to be in the loop on the project or conversation.
It comes down to consideration. In the moment, reflect and refine, can make you so much more efficient.