[PvK]

In Proportions, blockading can be useful against major planets (especially homeworlds, of course). Capturing planets can be much more valuable in terms of the amount of time saved, too, so blockading rather than glassing is also attractive.

It's not all that hard to do, either. Include planets in the "don't fire on" list, and either don't break formation, or include that prohibition in the design tactics.

If you want to blockade with a huge fleet, and need to avoid long-ranged weapon platforms, it may be helpful to break your blockade into a number of smaller fleets, so none of them start out in range. IMO this isn't too unrealistic either, as a planet with serious long-range weapons would realistically be harder and more dangerous to completely blockade.

PvK