"is if there is any benefit to entering the Form 5498 when received on its own"

No, because that form is not a Tax Reporting form. It is Informational.

"and so no 1099-R to accompany it)"

The 1099-R means something has to be reported to the IRS. That is for money Out.

Remember: Form 5498 = money In. It happens if there is new activity in that account, even if there was no corresponding 1099-R for money Out.

Example:

https://www.irs.gov/instructions/i1099r#idm140339526069312

"Transfers

Generally, do not report a transfer between trustees or issuers that involves no payment or distribution of funds to the participant, including a trustee-to-trustee transfer from one IRA to another IRA..."

Or, you need to show a deductible Traditional IRA contribution on your taxes, to take the deduction and there is no 1099-R, because there is no money Out.

The receiving account would still trigger a 5498, which would show the new money In. This is not a tax reporting form. This is Informational. Specific activities drive if something needs to be reported.

"to help keep track of the FMV for when a distribution is taken down the road? Or would this have no impact?"

Yes, you would keep track. No, it might not matter in any specific year. Yes, it will matter when Distributions happen. No, not all distributions trigger Form 8606 reporting, either.

You track Basis, but there is nothing to report to the IRS unless something has a tax impact. Example: Every year you put into a Roth account, there is a new Form 5498, but nothing to report for taxes and no need to fill in form 8606.

Read the Instructions for Form 8606 for Who Must File:

https://www.irs.gov/pub/irs-pdf/i8606.pdf