> Putting author names but no date at the top seems to be some sort of standard template or convention that every single paper author or institution everywhere uses since forever, since I never see dates at tops of papers.

The year usually appears in the bottom left of the first page, and in the header or footer of subsequent pages.

The first linked PDF [1] says only "14th USENIX Symposium on Operating Systems Design and Implementation" (without the year), but does have the year on an initial cover page. The second [2] says "HotOS ’23, June 22–24, 2023, Providence, RI, USA". The third [3] says "SOSP ’23, October 23–26, 2023, Koblenz, Germany" in the bottom-left of the first page.

However, this information may be missing from an author produced files/preprints, as it may be inserted along with page numbers when the conference proceedings or journal issue gets created. This seems to be the case for the fourth linked PDF [4].

[1]: https://www.usenix.org/system/files/osdi20-yang.pdf

[2]: https://jasony.me/publication/hotos23-qdlp.pdf

[3]: https://dl.acm.org/doi/pdf/10.1145/3600006.3613147

[4]: https://junchengyang.com/publication/nsdi24-SIEVE.pdf