You can tell a lot about a person by the words that they use. People who talk about “debt” are typically poor or middle class, and is more risk conscious than opportunity conscious. If there is not a balance of risk, you are going to end up not having enough money to retire on, or you will end up with a bunch of cash drawing tiny amounts of interest. However, more opportunity minded people (who tend to wildly vacillate between rags and riches) use the term “leverage.” While the middle class tends to want to zero down their mortgages, people who are really interested in building wealth are perfectly fine with taking on mortgages when the numbers work well.
When you first start out in business, the bottom line tends to be the main thing that you are watching. While you are obviously out to make money, in real estate that tends to start out being a long way off. It could literally be years until your rental or flip really makes you anything. However, there is a difference between watching out for the bottom line and being outright afraid to take on a mortgage, even when the numbers work and it will help build your wealth.
So when you get into a situation where a cash infusion could really accelerate your business interests, it may be completely acceptable for you to take on some leverage. Just make sure that you can afford the payments, and use the money wisely.