Why does "La Marcha Real", the national anthem of Spain, not have any lyrics?

There have been lyrics for this anthem but none are officially recognised, at least not any more. The lyrics that were used during General Franco's rule were officially abandoned in 1978.

https://en.wikipedia.org/wiki/Marcha_Real

In 2007, inspired by a performance of "You'll Never Walk Alone" at Anfield, the President of the Spanish Olympic Committee (COE), Alejandro Blanco, sought to add lyrics to the "Marcha Real", ahead of Madrid's bid to host the 2016 Olympic Games.

The TV channel Telecinco organised a national competition to find suitable lyrics. A winner was chosen, but only 40,000 people voted. So the COE organised another competition, which resulted in the selection of different lyrics. However, due to widespread criticism, the new lyrics were withdrawn after only five days and the project was abandoned.

https://www.elmundo.es/elmundo/2008/01/11/espana/1200036736.html