Based on my observations on what is happening and personal experience, this is most likely the case.
I think for spousal visas (IR1/CR1), the two most important factors NVC is using to determine which cases move to interview at USEM are the priority date and secondly, the DQ date. With all the delays at USCIS/NVC/USEM, the cases with the earliest priority dates are most likely already IR1s by the time the case is DQ'ed or CR1s converted to IR1s while the case has been sitting at NVC after it has been DQ'ed. When you log into CEAC, you will see your visa class change from CR1 to IR1 around your second anniversary date. If your case been DQ'ed late, then will probably have to wait longer than someone with the same priority date.
Whether the visa that is ultimately issued by USEM is an IR1 or CR1 is irrelevant. They are essentially the same except your visa says "CR1" if the embassy issues the visa within two years of your marriage and "IR1" if you have been married more than two years. Then, when you enter the US, if you are still within two years of marriage, USCIS will issue a 2-yr conditional green card or if you have been married more than two years, they will issue a 10-yr green card (even if your visa is marked CR1).
DoS statistics published only show the end result; that an IR1 or a CR1 was issued by USEM. Not what the visa class was when are at the NVC stage. Given the backlog at USEM, the vast majority of the spousal visas issued are now IR1s whether they were converted from CR1s or not. The CR1s you see in the stats are likely cases that have been expedited, not cases that moved forward on their own.
That said, there are probably other factors that are used by NVC/USEM to take action on a case. So anecdotally, you might see cases that don't fit with the above. But I think looking at the bigger picture, that is what has been happening.
It is extremely frustrating to be sitting and waiting and seeing a whole bunch of IR1s being issued while very few CR1s are being issued. Remember that if you take priority date into account, those with the earliest priority dates started the process earlier and therefore have been waiting the longest and ultimately are issued an IR1.