My guess is its a combination of a lack of effort (lead generation in particular) and a lack of financial planning.

For the sake of a little more clarity on the subject, unless one qualifies as a real estate professional, the depreciation will be limited to use against only passive income, which can include income from all of your rental properties combined.

We already had Cozy.co which is now apartments.com so we use them in combination with housters.

Some investors combine the strategies, and rent out the property during fall and winter to a long-term tenant as a furnished rental (think corporate rental), and then switch it over to short-term Airbnb style to get the best of both worlds.   

And if you’re married, that’s combined.

You will lose some money in the turnover, but you will have the tenants moved in under your terms.I bought a rental like that and the previous company rented per room, and it caused more calls for me than my other units combined. 

I'm sure many of you can remember the Global Financial Crisis that occurred between 2007 and 2009 due to the government’s encouragement of broad homeownership induced banks to lower their rates and lending requirements,5 which spurred a home-buying frenzy that drove the median sales price of homes up by 55 percent from 2000 to 2007.BAs a result, Banks were handing out loans like candy to anyone and everyone, combined with the explosion of the United States run-up in housing prices fueled by demand, speculation, and exuberant spending to the point of collapse.This crisis damaged financial institutions globally which led to a loss of more than $2 Trillion from the global economy! 

Although some have done so, and it will work for some buildings, I don’t think combining two units is the way to go here.

Combined with other losses, it is also possible to show a $400k loss for one of the partners.

You said you made it clear that you don't want fees taken out - how did you get them to accommodate that other than by meeting minimum balance or combined minimum balances?