think about a ground up construction deal, for a while in place income is zero while interest accrues. Eventually the value add is a massive swing and hopefully more than covers debt service. people buy deals all the time where in place income is low or even negative, but usually its a turnaround value add play. eventually the goal is to reverse that ratio.
cap rate less than interest rate doesn't necessarily mean negative returns, only negative effects of leverage. if you're looking for a long term buy and hold without a lot of potential value add, then absolutely look for deals with positive leverage. Some people using this strategy might be ok with lesser returns because: 1) they cant come up with the cash and need the debt 2) they are considering after tax results 3) market (non forced) appreciation if factored into their analysis by way of ever increasing rents or cap rate compression on sale 4) they just need a place to park their capital for the time being and real estate is a safe bet.
Hard to compete with many of these buyers if you are using a different strategy. A certain deal could be a homerun for one investor vs a dud to another, all because they have different goals and needs for the transaction.