LOKE,
Some older designs do not have auto-spoilers (suspect you are too young to know, but hey, thats alright).
Reverse thrust (by itself) does not stop aeroplanes (at least within the confines of most civil runways) and is not figured in the regulated stop distance anyway (FAA).
Ground spoilers without the application of auto/manual braking certainly does not stop aeroplanes.
Only one item that is available for the flight crews' use can positively stop the civil aeroplane...wheel braking.
Spoilers/reverse help, but cannot by themselves do the job.
Understand now?
