POLITICAL PARTIES PROBLEM

There is a well known situation/phenomenon in economy that, any market eventually tends to reduce to two big competitors/companies. Some examples of that are Coca Cola vs Pepsi, McDonalds vs Burger King, (Windows vs Linux?), (Chrome vs Firefox?), (PC vs Mac?), (Android vs IPhone?),...
I think another possible final market state/outcome is a single monopolistic company/product.

It seems to me that, general time evolution of multiple-political-party systems (in each democratic country in the world) is similar:
Either, finally, two big parties chaotically winning/losing elections, and so keep switching the control of the country between each other, like for example Democratic Party vs Republican Party in U.S.A.
Or, one political party eventually takes full control, and thus creates a dictatorship. 

I think it also seems that another general trend is, as time (years/decades) passes, overall/general loyalty/faith levels of members to their political parties also become more and more non-questioning/absolute loyalty.
This also means that general effect of political parties on their societies is to cause (keep increasing) social polarization (thru a positive feedback effect?)!
(Realize that, as members become more and more absolutely loyal to their political parties over time, views of other parties would be rejected/refused more and more strongly (and so keep taking a country towards a civil war!)!)
This also means that people vote, more and more, for the party, not for the candidate!
(So any/all bad personal character/personality/intelligence/education/experience properties of candidates would be ignored/overlooked, more and more strongly/widely over time!)

So it seems to me that there is really no good/stable long term outcome/state with having political parties!
Then what is the general long term stable democratic political solution (if there is any)?

How we can prevent increasing social political polarization over time?
How we can make sure people always vote for the candidate, and not for the party?
How we can create a long term stable and democratic political system?

I would like to ask, why a political system needs to have parties anyway?
Is there really any good reason(s) (I really do not know)?

Because it seems to me that, if there were no political parties (so, only independent political candidates are allowed, always), then, there would/can not, any long term increasing (political) social polarization in that society!
And people would be always forced to vote for the (independent) candidates, depending on their good/bad personal qualities, and not for their parties (since there aren't any allowed anymore), isn't it true?