So I see the reasons behind from reading a few threads.
Times have changed. If you make a static reservation for something on any newer device (I can vouch for these, Windows DHCP, SonicWall, Watchguard, NetGear, D-Link & Linksys) that IP will NOT be assigned to anything but that programmed MAC. Regardless if it's on or not. If the machine is off, no device can take that IP (unless you spoof the mac)
What happens is that it will take the next IP above it, for example
range: .100 - .120
ips: .100 - .105 in use
.106 is static reserved - but machine is off
new user comes in and is assigned .107 since .106 is considered taken
even in windows dhcp you will see inactive/active depending on if the machine the static mapping belonged too is on or off.
in real world scenarios where this is common some users machines will be assigned in the middle of near the end of the scope, we assign them that static IP and then program a port forward for their service (typically RDP) with it is now I would have to rework the entire scope to accommodate one user - in certain setups .2-.254 is dhcpd)