Below is the link on how to obtain a visitor visa to Canada
http://www.cic.gc.ca/english/visit/apply-how.asp#step3
Section 3 has the following
•You may need to include other documents. These documents could be identification cards, proof of employment, a letter of invitation from relatives or friends in Canada, or a proposed itinerary. Check the website of the visa office responsible for the country or region where you live for more information
The invitation letter is only one piece of the evidence that the Canadian immigration would like to have to show that you do NOT intend to immigrate and will return to your current country of residence. It is not an absolute requirement to have one, but helps in obtaining a visa.
Travel history is just another form of evidence. Good history would be visiting a country and leaving in the alloted time allowed, not overstaying. So as long as you can show that you have done this an not violated any other countries visa requirements, it should be satisfactory. But in the end, it will come down to someone's opinion