Broad statements are misleading.

Ignoring the context of the discussion is even more misleading. In the context of this conversation, ISPs providing consumer connections and obtaining grant money, my statement is 100% accurate.

That’s how you get fiber into a building or between buildings.

You just said multimode can’t do significant speeds at distance, yet claim that buildings separated by distance would be connected with it? That logic doesn’t hold.

Intrabuilding or intrarack Yes, you’ll find multimode fiber occasionally. But even these rare cases are increasingly replaced by single-mode as costs drop and bandwidth needs rise.

Everything else (ISP deployments, backbones, FTTH) Single-mode fiber dominates. I haven’t seen a single ISP deploy multimode for consumer-facing services over a typical network radius (~hundreds of meters to kilometers). The only minor exception is MMF from the building network room to an apartment unit, which is irrelevant for this discussion and would be EXCEEDINGLY rare as most buildings would just copper line to the unit. But even in that case... the 20+km from the head end to the building counts for much more than the 20meters to the unit itself.

For all practical ISP purposes, single-mode fiber is what’s in the ground/on the pole, and upgrades are handled via transceivers, not ripping out the cable.

OM4 multimode won’t push 10gb at 500meters no matter how good your hardware is.

But just because you said it...

https://www.corning.com/catalog/coc/documents/application-engineering-notes/AEN075.pdf

and OM4 is suitable for distances up to 550 m

https://www.fs.com/uk/blog/om4-multimode-fiber-faq-highspeed-connectivity-guide-9499.html

OM4: Supports 10 Gbps up to 550 meters.

https://www.timbercon.com/resources/calculators/om1-om2-om3-and-om4-fiber/

OM4 Not specified 500 m* 150 m 150 m
*The IEEE has yet to officially give a distance for 10GBASE-S on OM4 fiber. The distances are decided by the IEEE in 802.3, not The TIA or ISO/IEC cabling standards. Some glass vendors say 500 m, but most are now quoting “up to 550m.”

You absolutely can run OM4 at 10gbps at or over 500m depending on your optics/laser.

But Multimode was never the point of discussion as the whole thread is based around broadband services (virtually none of it serviced by multimode, if any at all) and grant money for rural area coverage. Any fiber upgrade in this scenario will 100% be SMF with no qualifiers. In my past 30 years of IT career all buried and pole mounted fiber is SMF that I've ever seen for an ISP. I can tell you for certainty that ever fiber I've buried in the past 10 years for several companies has been SMF. I'm not even sure that I've touched MMF in the past 5 years even in intra-rack setups, I think I might have gotten some with a government auction win about 8 years ago I wanna say? With costs of SMF at near parity for the cable itself and getting closer every year in the modules... it's a dying form factor and was never really in use for ISP services to begin with.

My fiber ISP runs single mode to my home. And it means it's all single mode on the pole for the neighborhood.

Multimode just isn't used all that much anymore. We replaced all fiber links in our DCs with single mode recently. It's just cheaper, and as the other person said: Its far more future proof.