I doubt you were actually asking but I'll give you the benefit of the doubt and give you an answer
because in a farming season a lock means it can't be farmed for up to 4 hours (whereas you could have let another guild come in to farm it if you'd already brought it to 159)
and in a competitive season, a lock prevents you from re-locking it when an opponent wakes up
About this topic...
The volcanic map and the waterfall map is somewhat different.
In the volcanic map, even the strongest guild would find themselves difficult to get out from the 159/160 blockage, even when they are strong enough to win all the racing situations.
When you try escaping from the blockage, you need 2 different routes to the sector in order to
gain control of it. One route is to attack and enforce owner change, the other is to attack right 4 hours after the first to actually capture the sector. You can't use the same route (except when you are attacking from the guild's base) because when the target unlocks, the first route would be taken away by the blocking guilds.
In the volcanic map, 2 routed attack is only possible for 2 of the surrounding sectors in addition to the 3 sectors adjacent to the base. Strong guilds may feel cheated when they are blocked by weaker guilds.
In the waterfall map, 2 routes can be found to the center of the map. And so, blocking strong guilds is rather difficult, and it is necessary to win races to keep the blockage. This means that strength of the guilds is more dominant in this map. Blocking don't look like a cheat any more, but in the realms, nothing really changed because in most of the cases, the blocking guilds are the strongest guilds on the map.