crespiI agree with the OP. While it is [sometimes] easy to find someones steam profile, it's not always as easy as you think. Several times I've had a hard time finding anyone on a team because they either have some stupid ass alias on esea, change their name on steam constantly, or their steam alias is very common. So it's not quite impossible to find people, but sometimes it's definitely a pain in the ass.
You're doing it wrong. You grab their steamid, not their steam username or alias, from their esea profile, under history, then you use steamidconverter.com, steamidfinder.com or google to find their profile. This will work every single time, with the exception that someone hasn't linked their esea profile to their steamid yet which you won't run into very often considering you need to link your steamid before you can join an esea server.