Please read the study and the CDC web page you're linking to. They don't support your point.
From the CDC link you provided:
> Doxycycline (100 mg orally BID X 14 days) is generally recommended for prophylaxis in adults.
From the study you linked to above:
> A single 200-mg dose of doxycycline given within 72 hours
The CDC recommends a 14-day course of twice-daily dosing (BID = twice daily). It has no relationship to the single-dose NJEM study you linked to above.
"In areas that are highly endemic for Lyme disease, a single prophylactic dose of doxycycline (200 mg for adults or 4.4 mg/kg for children of any age weighing less than 45 kg) may be used to reduce the risk of acquiring Lyme disease after the bite of a high risk tick bite."
You can also see their guidelines for doctors here:
https://www.cdc.gov/lyme/resources/FS-Guidance-for-Clinician...
Lyme disease treatment protocols are shown here: https://www.cdc.gov/lyme/treatment/index.html
Doxycycline is generally used for 14-21 days, twice daily, not a one-time dose as used in your linked study.
Even the linked study shows that Doxycycline acts on B. burgdorferi, even in the difficult stationary phase. Scroll down to Figure 6: https://www.nature.com/articles/s41598-020-59600-4 . Obviously Azlocillin is superior in this in vitro study, hence the news. But it still shows that Doxycycline is active against the bacteria. It's too bad that the authors didn't continue the test long enough to see Doxycycline either reach zero (presumably) or level off. Seems like a crucial piece of data that they strangely neglected to measure.