scoffing
I have played over 1000 games and it never happened to me. I guess you were unlucky. I also play csgo allot, there it happens almost every game, when it is onesided.
You should report such behaviour as it is of course against the rules.
Now, admins might do one of several things depending how serious was it and based on their previous behavior. They will not always ban for the first offense. Sometimes they might mute the account for some time, if the infraction is not serious or it is their first time to do something like that.
Apart from that, you may consider muting the chat in settings. You can , for example, set it in a way to mute it for everyone or mute it for everyone except for your friends.