well above method was only to tell u how to break password when u forgot urs,there r other methods also like by using "rescue mode" ,i m talking about changing ur password when u r the administrator,logged on,or wn u r unable to login cause u forgot ur password
nothin is related to hacking into someones computer its just a simple trick discussed here.
in industries u dont get access to root account,and if u want to login by second method ie by boot loader screen they have a boot loader password assigned so that u cannot edit at that screen,if furthur u have a cdrom of linux and u want to get access by "linux rescue",they dont provide cdroms in their pc,or its kernel module is removed.
no doubt linux is secure,the above method ws just to get access to your account wn u forgot ur password, as a good linux user u must know all these tricks

administrators dont make such mistakes

there r many other methods by which u can gain access to ur account wn u loose ur password. linux has many methods to do same job.

no doubt you are safe with the guard penguin