Elective deferrals in excess of 401(a)(17) - Fidelity's document

I understand it's likely permissible for a 401(k) plan participant to make elective deferrals on compensation in excess of the 401(a)(17) limit (assuming all other limits are not exceeded). Most plans I've looked at permit this with fairly obvious and simple language. Fidelity's document reads: 

In lieu of requiring an Active Participant to cease making Deferral Contributions for a Plan Year after his
Compensation has reached the annual Compensation limit under Code Section 401(a)(17), the annual
Compensation limit shall be applied with respect to Deferral Contributions by limiting the total Deferral
Contributions an Active Participant may make for a Plan Year to the product of (i) such Active Participant's
Compensation for the Plan Year up to the annual Compensation limit multiplied by (ii) the deferral limit
specified in Subsection 1.07(a)(1)(A) of the Adoption Agreement or Subsection 5.03(a), as applicable.

This is a strange way to say it to me. The AA has an elective deferral max of 100%, so pursuant to the formula in the above, the max a person's elective deferrals could be is $290,000 in 2021 (for a person whose comp exceeds 401(a)(17) in that year), and 402(g) would bring it back down to $19,500. Why does Fidelity's document make it this complicated? 

I'm guessing they are contemplating some lower deferral max, say 5%.  So that someone making $1M would in fact be limited to $14,500.  Possibly a holdover from the old (old!) days when PS was limited to 15% and deferrals counted as PS.

On 10/29/2021 at 4:17 PM, ERISA guy said:

Why does Fidelity's document make it this complicated? 

One word - lawyers.

On 10/29/2021 at 3:17 PM, ERISA guy said:

(ii) the deferral limit
specified in Subsection 1.07(a)(1)(A) of the Adoption Agreement or Subsection 5.03(a), as applicable.

ERISA guy, you're saying that 1.07(a)(1)(A) says 100%, I take it? What does Subsection 5.03(a) (probably a reference to the BPD, not AA)?

Section 5.03(a) of Fidelity BPD No. 17 covers catch-up contributions. 

Fidelity's 2020 BPD No. 17 restatement updates that language and may be more clear: 

"Rather than requiring an Active Participant to cease making Deferral Contributions for a Plan Year after his Compensation has reached the annual Compensation limit under Code Section 401(a)(17), an Active Participant may make Deferral Contributions until his total Deferral Contributions for a Plan Year equals the product of (i) such Active Participant's Compensation for the Plan Year up to the annual Compensation limit multiplied by (ii) the deferral limit specified in Subsection 1.07(a)(1)(A) of the Adoption Agreement or Subsection 5.03(a), as applicable. Also, rather than requiring an Active Participant to cease making Employee Contributions once the annual Compensation limit is reached, an Active Participant may make Employee Contributions until his total Employee Contributions for a Plan Year equals the product of (i) such Active Participant's Compensation for the Plan Year up to the annual Compensation limit multiplied by (ii) the contribution limit specified in Subsection 1.08(a) of the Adoption Agreement or Section 6.05, as applicable."