Sure, if you get good results with them, then why not.
I just wouldn’t recommend relying on affiliate marketing as your long-term monetization strategy. At the end of the day, business is about solving the problems of your target customers.
With your own product, you can simply tailor to the specific needs of these target customers much better. You can create a perfect fit between your free content and the product/service that you are offering.
This means that you don’t really need huge amounts of traffic to make a decent amount of profit.
With affiliate marketing, however, the margins are (mostly) quite small. This means that in order to make a full-time income, you will need to reach a huge number of people.
Most bloggers simply never reach those numbers.