How do sites prevent vanity URLs from colliding with future features?

It’s easy to check if a vanity URL collides with a current feature, but hard to predict everything you would like to build in the future.
Here is a list of some reserve keywords which can collide with the future features you would be implementing.
about
account
activate
add
admin
administrator
api
app
apple
apps
archive
archives
auth
better
blog
cache
cancel
careers
cart
changelog
checkout
codereview
compare
config
configuration
connect
contact
create
delete
direct_messages
documentation
download
downloads
edit
email
employment
enterprise
facebook
faq
favorites
feed
feedback
feeds
fleet
fleets
follow
followers
following
friend
friends
gist
github
google
group
help
groups
home
jobs
hosting
hosting url
hostmaster
idea
ideas
imulus
index
info
invitations
invite
is
it
login
logout
job
json
language
languages
lists
logs
mail
map
maps
mine
mis
news
oauth
oauth_clients
offers
openid
order
orders
organizations
plans
popular
post
postmaster
privacy
projects
put
recruitment
register
remove
replies
root
rss
sales
signup
save
search
security
sessions
settings
shop
sitemap
ssl
ssladmin
ssladministrator
sslwebmaster
stacks
status
stories
styleguide
subscribe
subscriptions
support
supportdetails
support-details
sysadmin
sysadministrator
terms
tour
translations
trends
twitter
unfollow
unsubscribe
url
user
twittr
widget
widgets
wiki
update
xfn
weather
xmpp
webmaster
ww
www
wwww
xml
yaml
yml