Here are 10 reasons why.

1. The reason the French did not do away with the French Closed Championships earlier and make it open was because the World Hard Court Championships was already providing a high class open event (open to all amateurs).

2. The event was held at the same venue that the French Championships was held (St Cloud, Paris) at the same time of year, with the exception of 1922, when it was held in Belgium.

3. The event was a World Championship, one of only three such titles designated by the ITF on its' formation. The other two titles were Wimbledon (World Grass Court Championships) and the World Covered Court Championships (this event didn't thrive like the other two, partly because of the scheduling and organisation of the event and partly due to the status of indoor tennis at the time).

4. The event was the top event on clay from 1912-1923. The term "hard court" was an old fashioned term for clay. The French was the top event on clay from 1925 onwards. This means the top event on clay was classed as a Grand Slam event back to 1912. Tennis wasn't played widely to a good standard for many years before 1912. Before 1912 the top clay court events were those on the early Spring Riviera circuit, where mens events attracted a number of top international players (womens fields were quite weak). Men's matches were often best of three sets (except finals). The Riviera circuit evolved as tennis established itself in Europe at the turn of the century. Top French player Andre Gobert said in 1912 in On the court and off "Until the year 1900 or thereabouts the French players could only boast of a fairly honourable standard of play. They considered the game more in the light of a pleasing pastime than as a real sport, and neglected all manner of training". Max Decugis was the first top flight French player (arriving just after 1900). Anthony Wilding commented in On the court and off that up until around 1908 the Riviera tournaments were quite light hearted events, but by 1911 had become a lot more serious, as a greater number of talented French players emerged who took the game seriously. To create an event recognised as the World championships on clay was the next step in the development of French tennis in 1912. By the time the World Hard Court championships ended in 1923, tennis was booming and Bill Tilden was the dominant force in a much more global game.

5. In terms of quality of the fields, the World Hard Court championships was considerably better than the Australasian/Australian championships of the period, which often struggled to attract all the top names in Australasia, let alone the rest of the world. Number of entrants at the World Hard Court championships were usually double that of the Australasian championships. The Australian did not admit women until 1922. The World Hard Court included women from the start.

6. The event was often referred to as the French Hard Court Championships. When the French championships began in 1925, this was referred to by the same name. Many regarded it as the same event. The only two differences were, from 1925 there was no closed championships and the World Championship tag no longer existed.

7. Although many historians have chosen to ignore the World Hard Court Championships, this does not detract from its' status. The important thing is how it was regarded at the time.

8. Although some of the players who did well at the World Hard Court Championships did not do so well at Wimbledon or the U. S., they were top performers on clay. All the best clay court players of the day entered the World Hard Court championships, just as they later did at the French. Clay has always been a specialist surface.

9. The reason the three World Championship titles were done away with in 1923 was due to pressure from the United States, who had continued to run a first class national championships throughout the period the three World Championships were in operation. However, the status was transferred to the French championships when it began in 1925 (in 1924 the Paris Olympics was held so there was no French championships), even though the World Championship tag was no longer there. This is why the French Championships didn't have to take years to establish itself. Its' pedigree had already been established by the World Hard Court Championships.

10. The World Hard Court Championships did not take several years to establish itself, because it was a World Championship and organised as such. This gave it instant status.