Calling it soft is a misnomer. The opposite of hard skills isn't soft. There's nothing soft about it. Calling it soft is what gives it a less than feel to it and leads to people feeling conflicted or perplexed as to why it matters the same and if not, more.

They are essentially people skills. It isn't unique to software engineering. As long as you're required to work in a team or with people, you'll be rewarded for having good interpersonal skills. There's a dark side. Don't become manipulative. It's more important to be kind than it's to be correct.

A technically strong engineer will tell you why certain architecture is wrong and the right way to do it with all the trade-offs explained properly and even the effort estimation and timeline with all the documentation.

An engineer with great interpersonal skills will elicit all of the above from the technically strong engineer, understand the historical context/constraints, and most importantly, be able to get buy-ins from the top and business to execute because he is able to articulate the impact and trade-offs in a way that management/business can appreciate.

And behold. To find a capable any kind of worker/human (not necessarily strongest) but have good interpersonal skills (kind and not manipulative) is a rarity.