There are many angles to this question. But the most common block would be your audience.
Think of it this way. What do you do in referrals?
You ask people to share your link with their friends and ask them to subscribe. But both of us know our friends don't do things on the first go.
So you build a reward incentivicing enough to put in the time and effort.
To run a referral program or not lies back on this exact same criterion—does your audience have time?
If you're running a marketing newsletter for newbies, it makes sense to ask for three referrals with an ebook as a reward. They have all the time in the world + they are on the learning curve + they operate on a budget.
But audiences like, say investors or founders or any ICP with time as scarcity wouldn't appreciate a program that demands so much of their time. They're happy to pay for the reward instead. That's your sign to sell an info product and not run a referral program. You will focus on monetization and find alternatives to increase readership.
The behavior patterns you look for are: "How much time does my ICP have? How easy is for them to just buy from me?"