Thinking about the original question, I've tried to take a step back and reformulate the question a bit: what is a bond, and why would one own a bond (or in the aggregate a bond fund)?
From a business finance perspective, a bond is a way to raise cash without selling part of a company. Funds are characterized as bond funds if they hold these financial instruments; not if they behave like traditional bonds. This is an important distinction because it affects what we mean when we talk about bond funds.
From an investor perspective, a traditional IG bond is a way to get a better return than in a bank. In exchange, one takes on a modest amount of risk, some of which can be diversified away in a fund. IG bonds preserve nominal principal, though inflation gradually reduces their value over time.
One diverges (slightly) from this traditional perspective of bonds as pure income streams when one starts trading bonds in an attempt to increase total return. This began in the 70s,
largely with Bill Gross and total return funds. These funds take on a measure of equity characteristics, especially as they add junk bonds. At this point, ISTM one is at the edge of crossing over from "bonds" to "allocation" funds, in behavior albeit not in name.
Moving on, multisector bond funds behave significantly like allocation funds. But because they're still bond funds from a finance perspective, people can feel good about eating their vegetables - investing in "bonds" while getting better returns.
Here's Portfolio Visualizer's
correlation matrix of a "pure bond" (albeit leveraged) multisector fund PDIIX, a multisector fund with a 13% equity kicker RPSIX, and a rougly 40/60 allocation fund (disregarding cash) FTANX. The five year time frame I selected is the period covered by PDIIX's current management team including Ivascyn.
They're all pretty well correlated. Further, annualized standard deviations are quite close together, ranging from
5.62% to
5.84%. In terms of risk and performance these multisector funds feel like hybrid funds.
I do own a multisector fund (none of the funds here), but I expect it to behave like a hybrid fund. It's just another way for me to get that risk/reward profile.
To the extent that I use IG bond funds, they're there to serve as the last bastion before dipping into equities should stocks swoon for several years. On the short end, I use short/ultrashort funds as backup to pure cash - a bit more return in exchange not drawing upon them monthly in case of hiccups.
I've no bond funds for a traditional, widows and orphans, monthly pension type cash flow.