Extremely not-fun fact: collectively, humanity currently produces more than enough food for every person. But a huge part of it is either wasted or inaccessible by people that need them, which usually results in them not going to anyone and being wasted, which is why we still have food scarcity.
There are exceptions, but a general rule is that if you invest more resources in growth your investment in pest defence will go down. So plants bred for yield often have reduced pest tolerance. But yes, they are in many cases interbred with more resistant varieties to (partially) compensate.