Some of the givingest churches it has been my honor to be part of were not able financially or in some cases, such as in lease camps, not allowed to build a building or pay a staff. God provided us with able men to step up from the ranks and serve as the preacher.
Because we had no overhead, we were able to support the state children's home, the home and foreign mission boards, tend to the "widows and orphans", help with educating future pastors, etc. Don't assume churches that do not teach the tithe are full of slackers who do not give.
And some of the financially richest churches full of tithers were poor stewards, focused more on building a personal empire and big building than on winning the lost. Some tithers figure they have done all that is necessary when they write the check.
My point stands. The tithe is not an obligation for NT believers and yet at the same time can be a very rewarding benchmark in helping us learn stewardship. But let's not kid ourselves that the work of the Kingdom is dependent upon money. It simply isn't.
Money is a very good tool that can aid tremendously in spreading the gospel. It can also be a trap Satan uses to block that spread. But even those who cannot tithe can contribute mightily to the growth of the Kingdom.
This is just personal experience and your mileage may vary, but I'd much rather be in a church where tithing is beyond the reach of many than in one where it is easy and commonplace. Those in the first will often give sacrificially of money, time, talent, and skill. Those in the second usually complain about everything.
And again, if you believe to be a church requires a paid staff, or a building, or any other overhead then as a believer it is your responsibility to help provide those as you are able. But many of us have experienced a more basic form of church and know you don't have to wait for the money to start up, or have to fold when tough economic times dry up the kitty.
Sacrificial giving in those cases may mean sharing meager food with someone hungrier, or giving clothes you need out of your closet to someone in more need. It may mean stopping tithing so you can take in a relative's child or pay a doctor bill for someone out of work.
But I agree with you completely that churches with building ownership and paid staff must be properly funded. Too often folks want the amenities, want staff to do the work of the Kingdom, and want to sit on their wallets.