That statement is only true for a few of the things on your list.. Yes, it took a couple of decades to test the existence of neutrinos. But, for example, gener

That statement is only true for a few of the things on your list.. Yes, it took a couple of decades to test the existence of neutrinos. But, for example, general relativity was successfully tested within 5 years of being published. Gravitational waves were a prediction that took decades before we could test them, but the theory itself had lots of other verifications. To date string theory has had many predictions that leads to failed tests. But not a single successful test in its favor.