Besides further homogenisation of factions that a lot of people already complain about;
Everything major that gets changed will have ripple effects. When RE got snares and it was finally no longer possible to park light vehicles on top of UKF infantry without consequence, the faction turned OP almost overnight and needed some significant nerfs in other areas to compensate. For example, if you'd add a snare to Infantry Sections, the AEC would become significantly less mandatory, and that would very likely in turn significantly speed up their tank timing. They have the cheapest tank tech of any faction, this is balanced only by requiring to get some side techs along the way. So yes, big changes like adding snares to a mainline or adding stock rocket arty would definitely require more reworks and rebalancing down the line. It's never simple.
Absolutely, I get it, there's some changes that would be needed. What I meant by that is that it would not require a complete overhaul and unit switch between tiers like OKW and USF did.
The more obvious issue is medium timing, but that would be imo the easier to solve. Since the faction timings are currently balanced by considering AEC a mandatory requirement, by adding both AEC and Bofor unlock as a single upgrade costing 100 mp and 15 fuel in the Platoon Command Post the faction would keep the same timing for the Cromwell and have the option of a backup at light vehicle.
I'm not downplaying the overall changes in faction strength, sure it would make UKF infantry more potent during the light vehicle phase, so overall a lot of smaller changes would be necessary with 2 matchups to be sure that, for example, OST can still compete against a UKF that can more easily snare their 222. All i'm saying is that, compared to what OKW and USF went through, it would just be a portion of the effort.
Regarding the "homogenisation" issue. I don't think that it makes sense to draw that line right at snares for mainline infantry. We had 2 men sniper squads for a long while but that was cancer. I don't think that UKF would lose their identity just because of snares.
But regardless we could at least have a middle ground with AT boys tank hunter sections made non doctrinal as option to build after Tier 2.