Well… there is some truth here.
It is true that one can live exclusively with security solutions that don’t cost anything.
But, there are other costs associated:
– overhead in the maintenance
– consume more resources than if they were in one solution
– Ads (free products use the concept of “freemium” or are ads supported)
– less features and sometimes less security (but not always!)
For more details, check this article I wrote for (ISC)2 Blog: Security for Free?
All these and many more topics are in the free eBook "Improve your security" available here: www.improve-your-security.org.