I have mixed feelings on that comment. It has already been mentioned that science fiction evolves with science, but it's also worth noting that a lot of the old works had less to do with science than many modern works and many old science fiction ideas are not even classified as science fiction anymore.

A lot of that old SF had to do with topics that we've long since moved on from. The modern world has a different view of space travel. Some of it is routine, like satellites and robotic science missions. Some of it we've all but given up on, such as manned exploration. The former is not science fiction, it is reality. The latter is as close to unicorns as you can get without abandoning reality altogether, short of orbital missions (of course). Even then, that old SF didn't really stick to science. More often than not, things were made up for interstellar travel and the sluggishness of travel within our solar system was usually ignored. We have also picked up a lot of new themes as well, such as artificial intelligence and bioengineering. Some of these are as scientific as the old works, preferring to focus upon the social. Others are quite bound by science.

Even so you have to consider that some forms of science fiction are not even classified as science fiction anymore. Those old SF mysteries, some of which are bound by science and some of which are unrealistic, are now just mystery or law stories. They'll still have forensic science, but there is nothing special about it. Ditto for a lot of the stuff that has to do with computers. I recall an old Asimov story about human computers which is laughable these day, yet computers and communications technologies are integrated into books of all forms these day.