It seems that either there are no strongholds or that the eyes of ender do not work as intended. I have spent a lot of time following eyes of ender to random spots just to dig down and find nothing. Either that or the eyes lead off the world border. This is quite frustrating as a stronghold portal is needed to tech up from age 4. I have used the nether portal to go to the end and I didn't get the advancement. I wouldn't care much about the stronghold if we didn't NEED it.