Though the views that you describe are in fact an accurate description of what was true in the past, that is what they are accurate for the past. In the current NFL, the one the article correctly describes as a heightened interest in drafting safeties high the past 2-3 years, which was seen in the simple fact that two safeties were drafted in the top 10 last year and three in the first round and most important for those who are more interested in the reality of on the field accomplishments rather than the often misleading draft stats, safety is really an important part of the Cover 2 rage sweeping the NFL (which Jauron and the Bills have endorsed.
Your views of safeties being easily found in the later rounds have simply been passed by by the times.
One can hold onto the past draft numbers, but in doing so a person is building their views on what works in the past and in fantasy leagues rather than what works now in the reality of football.