Real life
Sorry you are frustrated.
Unfortunately this is s game and sometimes real life interrupts. Missing war can happen due to many reasons:
broken phone/ locked out of account
Sickness of family member, or self
Work emergency
Forgot before trip/ vacation
Problems with individual opt out
etc.
Opt out
The devs resisted adding an opt out for a long time because it causes customer service problems ( see notes).
Eventually they were forced to add an individual opt out due to their choice of matchmaking.
Since the individual opt out triggers after 2 missed wars, the Devs are unlikely to do anything about people missing 1 war, or even 50% of wars ( example missing all Wednesday wars ).
Kicking
After matchmaking is done, if a teammate leaves the alliance, or is kicked, their defense team stays for the war.
The Devs are unlikely to do anything about a player missing 1 war.
Control
Similar issues are often discussed ( see links below)
I want people who are unhappy to leave so other people can try out our alliance.
I want people who might be a good fit for our alliance to have no artificial barriers preventing them from popping in and checking out our alliance.
Trolls
BoH had a problem with roving groups of Skunk mercs who deliberately messed up the game for alliances. Since Empires does not have a leaderboard / mission for wars, this is unlikely to be a systematic problem.
If you have good reasons to believe they are a troll. Take a screenshot and email it to yourself with the date and time. If they act like a troll in the future, you will have evidence for customer support. The Devs can not temporarily/ permanently ban a troll without proof.
I usually wait for 3 incidents to increase the likelihood of customer support taking me seriously.
Tracking trolls is one reason we are not allowed to change our account names.
Notes
Quotes
Links
(Control new player in Alliances - #4 by Gryphonknight)
(Prevent players from leaving an alliance immediately after joining - #15 by Gryphonknight)