Not true. The top vote getter might siphon off enough votes from their party's second place finisher that it drops them to fourth overall. Some of the voters will have "wasted" their vote on the party leader who would've been elected anyway even if they voted for the next highest party candidate. Think of two parties splitting the vote 60/40 overall. One party's votes are split 45/15, the other's 20/20. In a "top 3" scenario, the minority party gets two spots to the majority party's one.