The bottom line of all this is that even if you use Office 365, and you think that you have disabled Groups in your tenant, the chances are that you could be in for a surprise. If any of these dependent services are in use, the chances are that you already have several created.
Groups are the bedrock of all new features in Office 365 moving forward – it is therefore a good idea that your organization understand them as soon as possible. Their inevitability is also another strong argument for paying close attention to them. If you are currently discussing whether or not they should be used, I would strongly encourage you to shifting that discussion to how they should best be used.
Read the whole thing if you’re getting into Office 365.