Some cue builders build cues as art, that's cool. Don't expect them to be played. Most respected cue builders build pools cues because they are passionate about their craft and have worked years on playability. If all you care about is profit so be it, reputation and quality mean more to me.
Not even going to respond to the first three sentences of your post but will the last one. Yes, a cue maker may well be passionate about their craft, they still have to eat unless they have some bottomless pit to draw funds from. Reputation and quality get you those funds. You would be hard pressed to make me believe that they would work so long and hard if there was not financial reward at the end. The three go hand in hand.
As to your OP, as stated before, why should it matter? Once the cue is sold it is they buyers property. What he does with it is his business. While ones ego may want to determine what the new owner does with it is irrelevant, do you think the car dealer cares what you do with your car after you buy it? Should the cuemaker be upset at a customer that buy 6 cues knowing that 5 of them will stay in the closet?
As a seller of aftermarket shafts.... Most cuemakers do not make LD shafts as commonplace. Since they have now been around for well over 20 years and there is a known market for them it seems somewhat silly to be surprised or upset if someone buys a cue from someone and then buys a certain shaft from someone else. I sell shafts as partials so the customer can order a cue and have the shaft they wish finished by the cuemaker they wish. If the cuemaker does not want to do so than so be it, why is it an issue either way?
A buyer is not bound to a cuemaker because he buys a cue from them any more than the buyer is bound to the shaftmaker because he buys a shaft from him. Believing otherwise is folly and you are letting your ego get in the way.