[yafujifide]

No they don't. See the link posted by the author:

https://github.com/bitcoin/bitcoin/blob/11adab39e6019935aa3a...

Full nodes validate a lot of blocks at initial sync, but not all of them.

[Sir_Substance]

And here's my rebuttal to that misleading link:

https://news.ycombinator.com/item?id=17233986