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They are only beneficial if used in conjunction with a full antistatic workstation - a static dissipative bench top surface and floor mats etc.
Damage from static is due to potential differences at the instant something is touched to something else.
IF everything a person can touch is already equalised to the workstation, then the person also being equalised to that works to prevent harm.
In a normal situation where items could be at random potentials, a ground strap is no benefit at all and is more likely to make someone ignore good component handling procedures.
Handling procedures are critical; always pick up parts by the antistatic packaging or by initially touching metalwork, grounding screens, ground planes, power connections etc. so any voltage difference to your body is equalised via a path that is not sensitive to possible brief current spikes.
Likewise, when going to fit a component or board you are holding, touch the metalwork or ground of the item it will connect to, before fitting it, and try to maintain contact during the procedure - eg. if working on a PC, keep one arm resting on the case metalwork.
[It's an application of "relativity" - it makes no difference to anything if you an everything you are working with have a static charge to ground of eg. 2000V, as long as there is no voltage difference between you and the things you are working with; grounding yourself while other things still have that random charge = Zap! on contact].