Yes, because this will lead to wrongful assumptions about other people, if not contempt or mistreatment. Even ignorance can be racism too, though more harmless than willing hatred of other races.
"All Asians eat dogs"
"All Whites hate other people"
"All Blacks are aggressive and unintelligent"
"All Middle Easterners are violent"
If someone were to think like that, they would hate those races or avoid them, even if individuals from those races are decent people who do not fit those stereotypes.
To be honest, I myself do have some racism as well: sometimes I may be upset or suspicious towards some people, especially non-Malaysians, and sometimes I watch racist stereotypes for my own entertainment.
The ones about my own Chinese people amuse me, because they look ridiculous compared with other Chinese people. The old-fashioned ones about fine-robed "Chinamen" are rather fascinating because they look so foreign and different from most modern Chinese like me.