I don't have the data I need to drive relevance in my email. Look, while data is necessary to drive relevance, it doesn't mean that you have to be able to access and leverage every piece of information you have available on your customer base. Just leveraging one data point can increase the relevance exponentially, so don't discount the ability to improve experiences just because you can't wrap your hands around all your customer data. Sometimes a little bit can go a long way.
I don't have the content necessary to support relevant targeting. Content is a big part of relevance, but it is not the only thing. You can create relevant experiences through timing such as following a purchase or an abandoned cart. So if you don't have enough content to address the relevance, then consider looking at events or natural trigger points that would address a specific lifecycle point that is easy to identify and message against.
I don't have enough people to do the work. Resource strain is a consistent issue for marketers across the board. Look to your email deployment tool to identify technical solutions that will streamline, automate or optimize your production and deployment processes. If all else fails, look to a contractor --many are very good.
Motivational author Napolean Hill said, "The best job goes to the person who can get it done without passing the buck or coming back with excuses."
Do the best job that you can with the resources and data available to create the most relevant experience for your email subscribers, and stop making excuses. I am calling your BS: Just do what you need to do.