So then, would you agree with the statement: In striving to make the party appeal to everyone, the party can only succeed in appealing to no-one; by standing for nothing it only attracts those who will fall for anything.
You do not need to appeal to anyone outside your coalition partners ~ the reason is that among politically motivated folks, who can be expected to vote, they are NOT going to switch and vote for the other guy.
Your best source of new voters is among the 90 million adults who don't vote. Your worst source of new voters is among the other major coalition party's members.
The italicized statement you posted would not be a way to win elections because, as it turns out, when you stand for nothing, appeal to no one, and imagine you can win anything, you will be amazed every time you try it! We won't be amazed however.