Raiding people you know is perfectly fine. And setting up a raid chain is a great way for everyone involved to grow. But I would advise against raiding strangers you had no prior connection with. While most smaller streamers, who want to grow, wouldn't mind the extra viewers, it can create a feeling of having to give something back. And that can be awkward for many.
And raiding people you don't know and have significantly more viewers would often be received negatively. It's almost the same as spamming your Twitch link in their chat.