While this is true for an individual investor, a large part of the market for fixed income investments is large investors who are liability matching in one way

While this is true for an individual investor, a large part of the market for fixed income investments is large investors who are liability matching in one way or another: either against a portfolio of life insurance policies or against defined benefit pensions. They genuinely don't mind if the value of their bonds falls due to rates movements because (if they have done their jobs right) the value of their liability stream will also fall by a corresponding amount. Of course, you can then apply your argument to people who have pensions or life policies I suppose but those aren't things people often "sell".