None of that is true. It's really annoying to see it repeated. It's even been covered on HN
https://news.ycombinator.com/item?id=7304188 before.
There are parts of the F-1 engine that would be difficult to exactly replicate because while the engineering specs are known the exact fabrication processes weren't all documented. An exact workalike could be made for those parts that fit the specification without a problem. That new engine would need to be entirely requalified for use.
The F-1 is big and expensive and rebuilding them has long been outside of NASA's budget. If they were going to rebuild the F-1 it would be the same expense and effort to just design an entirely new engine.
This is why, for instance, the SLS is using the SSME as its first stage engines. It's a known system with a long and successful (the engine itself) flight history. It's been iterated upon and is well understood.
The design philosophy of rockets has also changed from the 60s when the Saturn was designed. Solid fuel boosters were not considered useful for Saturn but have been proven since then and have a long flight history. There's also the SpaceX/Soyuz model of an array of smaller/simpler engines. A small number of monster engines is just not needed like it was for Saturn.
The expense of the F-1 and the lack of real need has kept NASA from using them, not some loss of technology. The guidance systems...are a long long solved technology. Modern guidance systems are better than the Apollo and Saturn systems by orders of magnitude. They're far smaller which allows redundancy and still lower weight than old systems.
Since Saturn NASA has launched successful probes to every planet in the solar system and several dwarf-planets, landed several extremely long lived rovers on Mars, launched hundreds of satellites, over a hundred Shuttle missions, and assembled one of the most complex machines ever in orbit.
What's sad is the mistaken belief that Apollo was some pinnacle of capability and technological prowess for NASA.