[MT nester]

the point of the "desmo" valve train is preventing valve float at super high RPM.
This setup was invented out of desperation about 99 years ago when steel valve springs were primitive.
Ducati still runs this setup but only as an idiosyncracy.
The ultra high RPM systems in use in Indy cars running over 20,000 RPM use air pressure as a valve spring although modern steel springs would work.
They are using air pressure because at low RPMs less pressure is needed and by using air it is easy to modulate pressure in the system. Low RPM = less air presure,high RPM= high pressure. The reson for lower pressure at lower RPM is less friction on valve train components and less stress.