Why are elections based on a plurality system discouraging to new party formation?

Plurality requires each party to be as narrowly based as possible, leaving little room for new parties.

Under this winner$-$take$-$all system, no incentive is given for finishing second.

Plurality requires parties to form alliances with other parties to win elections.

Plurality gives an advantage to savvy political unknowns who can grab the media spotlight.

Only parties receiving more than $5\%$ of the vote are allocated seats.