One is targeted at DM techniques. The other is targeted at possible RP actions.
Question A (Shops) is about homebrew DM techniques. DM techniques, even for things that don't exist, can be opinions reinforced with experience or examples of similar materials from the in-game rules. It has a foundation to work off of, and few are refutable. Most answers can be applicable to most settings.
Question B (BBEG) revolves around PVP. Player vs. Player interactions are things that are rarely used in tables, and doesn't have much mention in any of the books available to players. On top of this, the offender to the party is described as being an RP-specific player, and the ones he's targeting are less so and focus on stealing/combat. There are plenty of things that can be suggested, but many of them are things that simply won't work for several situations without excessive explanation from the questioner or the questioner's DM. Even with experience from people who have been in a similar circumstance, the events would be very specific and likely non-applicable.
If 100 random answers were given to both Question A and Question B, Question A would have a lot to choose from, but a few would be filtered out due to an odd setting or DM's rulings. Question B would have a lot that would be wasted due to the fact that the answerers don't know what's applicable to the setting, players, or DM's decisions.
That's the main concern. We don't need to know all the variables for Question A for answers to be applicable, but we do for Question B.