You are right - as others said, bigger numbers mean more active ingredients in a given weight of fertilizer. Since the proportions are the same for both (10-10-10) and (4-4-4) the two are interchangeable, but you need to apply 2 1/2 times as much 4-4-4 to give the same "dose" as the 10-10-10.
For "amateur" use, relatively weak formulations can be easier to use, because you don't have to measure out and work with very small quantities, and you are less likely to "burn" an individual plant by applying too much if there is uneven distribution of the fertilizer.
On a commercial scale the reverse applies - nobody is going to want to handle 25 tons of 4-4-4 material when 10 tons of 10-10-10 would do the same job, and is perfectly safe for the plants if it is applied accurately using the correct tools and machinery.
How fast the fertilizer is released into the environment is a completely different issue, and (in general) that is independent of the concentration of the active ingredients. For a given formulation, "all" the active material in whatever "dose" you apply will be released in a fixed amount of time (which might be anything from a few hours for a liquid foliar feed, to a year or more for long-lasting soil conditioner). Of course, the plants may not be capable of using everything that is available if you apply an "overdose", and the excess amount may damage the plants.