I think the comparing architecture firms and sign shops is a bit of a stretch. There are important differences to consider.
Architecture firms typically "front" design work and have been long before crowd-sourcing became a thing. Often firms respond to an RFP (request for proposal). The firm will create a design concept and submit it to the potential client, who will be receiving multiple proposals from multiple firms. The client then chooses which proposal they will go with. This is all done before and significant amount of money changes hands. Where architects make their money is providing the construction documents and project management services.
The chosen proposal will then move on the next design phase where the specifics are hammered out. Often the firm receives a retainer and design work is billed hourly. The retainer for a small project (one million dollar) can quickly get into the 20,000 to 30,000 range. This is used to produce documentation to get the stakeholders on board. Finally once the design and budget is approved by the stakeholders construction documents specifying the project are produced to the tune of 40,000 to 50,000. Once the job begins project management fees could be another 50,000.
That is why they give away "free" work. A small firm may only need a dozen projects a year to be successful. One large project can provide 500,000 of income over two years. The 40-80 man hours to contribute a concept is the cost of doing business.
As for why the architects don't get off their *** and do it, they could but they are not going to spend the time and resources pursuing this project, they are going after others.
Architects, like all designers, like awards to hang on their wall. The awards do far more than fuel an ego. They provide leverage in the RFP process and are a promise of the quality of work they can do for a client if they accept the design. Work which will be billed out at a minimum of $150 an hour and up to $500+ an hour depending on the reputation of the architect.
I'm the National winner of the 'Such & Such Sports Complex' for 2015. Please, use me for your next project and I'll basically work for free for you, too. It's not about the money, but all about having a nice title hanging on my door. The more titles and credentials I have, the better I feel about myself. Next week, I'm gonna do a seminar on how I generate these logos. You too, can work for nothing. I'll show you how............. 
