Before I go and make a huge post, please give me your definition of "close" and "tank"
Assuming "close" means "really has several similarities to" and "tank" is being taken more or less in the WoW meaning of the word, lemme try this:
http://www.guildwars2.com/en/the-gam...healing-death/
Every class will have healing abilities, every class will have ways to control and support, and of course do damage. So, while the Guardian may have strong support abilities, he/she will still be a very long way from tanking (again, assuming by tank you mean the wow sort of tank)
If, on the other hand, by "close" you mean "reminds me a bit of palis in the whole holiness thing with light and stuff" and "tank" you mean "helpful heavy armour wearer who occasionally prevents death", then I completely agree with you - but we may be speaking a language that is not very "close" to English