I think the overall thrust of the article — "always try to negotiate, try to get better at it, it's low-downside and high upside" — is still very relevant and I frequently share it with friends interviewing even today.
Some specific things haven't aged well from this article in my recent experience:
1. Many companies have comp bands advertised and enforced by local law, and even outside of this many have implemented more regimented/structured comp in an attempt to reduce bias.
2. Relatedly I've seen more companies take a "no negotiation" policy, especially for more junior roles.
3. The market overall is much more an employer's market and is not growing as quickly, so the median SWE has less leverage.
I think the biggest impact of these changes is that the cost of not negotiating has become lower, and consequently the upside to negotiation is less, especially if you don't have competing offers or are more junior.
That said: competing offers is still the single most effective negotiation tool, as others have said. I've seen companies be relatively inflexible on cash comp but highly flexible on equity comp, which tends to not be required as part of job listing bands, and becomes the lion's share of comp as you get more senior. And often there are carve-outs of matching offers.
TL;DR: Still worth a read, but many of the specifics need discounting.