False, the FIFA rankings are in fact calculated in such a way that teams who play lots of friendlies are disadvantaged. Because a team's ranking comes from the average point score they get per match, with match-importance being included as part of that, friendlies in fact drag down the overall average. A team with a 9-1 record who has earned 5 of their wins in friendlies ends up with a lower FIFA ranking than a team with a 4-1 record who didn't play a single friendly match.
For a real life example, from July 2014 to July 2015, Slovakia had a record of 9-0-0, with 6 of those wins being in competitive fixtures (i.e. qualifiers). Wales, on the advice of a consultant, didn't play friendlies at all, and finished with a record of 4-0-2 that year. Wales had a significantly higher "point value" per match and got a higher ranking position because friendlies dragged down Slovakia's average.