@Adam665
Maybe he does have a profile picture but it is hidden until the booking is done.
There are many first time users here and if I would decline all of them I would lose half of my guests. But your concern is understandable, especially if you don't live there so it is better to be safe then sorry.
You have 24 hours to decide if you want to decline or accept this reservation. Use this time to communicate with them, find out how old are they, why they want to rent your house, are they couples or singles, etc... and then decide.
To protect themselves, hosts use whatever they can - security cameras, house rules, security deposits, personal check-in, mandatory photo ID check at arrival, mandatory light cleaning/sheets change 1xweek (to check if everyting is ok) ... and we can also set "booking requirements" who can or can not an instant book.
But yes, bad guests are always around the corner and the damage they can make may be very costly. I like to say we are all playing Russian roulette here...