Contrary to popular belief, you can compare apples to oranges
Apples and oranges can be compared, just as equities can be compared to bonds. Apples and oranges are both fruits with complementary characteristics, and when blended one has a fruit salad. When one blends equities with bonds you make a balanced portfolio.
The quality of the fruit salad depends on the the apples and oranges plus additional ingredients, hopefully complementary. Choices include grapes, kiwi, strawberries, apples. Bananas help, but are time-sensitive. If you want to ruin the mix, try lemons and limes.
Keeping with the analogy, a mixture of bonds and equities plus cash makes for a nice mix. Destruction comes with low quality, too much of one asset and non complimentary assets. Worse is overwhelming the mix with the flavor of the day. A fruit salad with too many grapes is as bad as a portfolio with, for example, too heavy a weighting in infrastructure assets, now a very popular ingredient.
Seldom will one find a low quality fruit salad, home or away. Not so with portfolios.
On a final note, watch out for bad analogies!