There are times when a seller does not want an address published. This might because of elderly or infant residents. It might be because they don't want their neighbors to know they are selling. I know the 'neighbors' issue sounds far-fetched, but I have had this be a reason for "no sign" and for "no address" on a few instances.
Unless a seller instructs me to withhold an address, we publish it. But, we will always honor the wishes of the seller, after a thorough discussion of the pros and cons.
Sometimes, it is the decision of the agency, not the individual agent. The agent must comply with the rules and guidelines of the brokerage for which they work.
I fully understand your frustration. I advise my seller clients that mulitple pics, and thorough info (address, detailed feature info, etc.) is extremely important in attracting more potential buyers.
I have had sellers ask me to remove their address because an aggressive buyer knocked on their door without an appointment and without a Realtor.
There are times when the address is missing solely because the agent wants the inquirer to phone for more info. But, that isn't the only reason as referenced above.
I hope the additional info helps shed light on the fact there are several reasons why this may be. Again, I understand your frustration, because easy access to complete info makes the process easier for you. If you have a buyer agent, you can rely upon this person to provide you any missing details in a prompt manner.
Best of Luck in Knoxville!