French Ligue 1 is de-facto considered to be in top 5 for several reasons:

 - It is more competitive:
  - [French Ligue 1 during Professional Era][1]: **19** teams have won it, **9** winning it 3 or more times
  - [Russian Premier League][2]: **8** teams have won it, **5** winning it 3 or more times
  - [Dutch Eredivisie during Professional Era][3] : **7** teams have won it, **3** winning it 3 or more times
  - [Portuguese Primeira Liga][4]: **5** teams have won it, **3** winning it 3 or more times
 - [Average attendance][5] is higher (stats as of 2015/16 season):
  - French Ligue 1 (which has 20 teams): **20,976**
  - Dutch Eredivisie (18 teams): **19,412**
  - Russian Premier League (16 teams): **11,049**
  - Portuguese Primeira Liga (18 teams): **10,860**
 - [Higher salaries][6]: (as of 2014)
[![Higher salaries][7]][7]
 - And finally, probably because France is a bigger player in European and World football as a winner of World Cup and two-time champion of European Championship whereas the others in question winning only European Championship once. (*Although, national team strength does not necessarily imply the team strength of its league, at some degree it can be the judging factor why French Ligue 1 is in the top Eureopean Five*).

Besides that, the only practical scenario when being in top 5 actually matters is when deciding the winner of prestigious [Golden Shoe award][8]:

> Golden Shoe is awarded based on a points system where the weightings are determined by the league's ranking on the UEFA coefficients. Goals scored in the top five leagues are multiplied by a factor of two, so players in tougher leagues have better chances to win.

  [1]: https://en.wikipedia.org/wiki/List_of_French_football_champions#Performance_by_club_in_Professional_era
  [2]: https://en.wikipedia.org/wiki/List_of_Soviet_and_Russian_football_champions#Total_wins
  [3]: https://en.wikipedia.org/wiki/List_of_Dutch_football_champions#Titles
  [4]: https://en.wikipedia.org/wiki/List_of_Portuguese_football_champions#Performance_by_club
  [5]: https://en.wikipedia.org/wiki/List_of_attendance_figures_at_domestic_professional_sports_leagues#Outdoor_sports
  [6]: http://www.dailymail.co.uk/sport/football/article-2833020/Premier-League-wages-dwarf-Europe-flight-players-England-earning-average-2-3million-year.html#i-ed75cc237f3a130
  [7]: https://i.sstatic.net/F6YUm.jpg
  [8]: https://en.wikipedia.org/wiki/European_Golden_Shoe