Your question applies to electrical appliances everywhere in the world. That article is accurate about voltage variations that are problematic for motorized appliances and irrelevant to electronics. Appliances have voltage ratings for continuous operation. Wider numbers apply for intermittent voltages. For example, properly designed electronics (even before PCs existed) would routinely withstand up to 600 volts without damage. Today's electronics are typically more robust.
Motorized appliances may be at greater risk due to voltage anomalies. And not just due to voltage variation. Other anomalies created by a UPS in battery backup mode can create problems for motorized appliances. That same 'dirty' power is perfectly good for electronics.
UPS provides temporary and 'dirty' power during blackouts - so that unsaved data can be saved. It does nothing for electronic hardware protection, does not claim to, and can be problematic for life expectancy of motorized appliances.
Numbers for those trends vary based upon 120 or 230 volt operation, time, and other factors. But that article is quite accurate. It contradicts many who are only educated by hearsay and advertising. UPS does almost nothing for protection of electronic hardware. Otherwise one could provide numbers for each electronic part that is harmed without a UPS.
You concern is a rare anomaly, maybe once every seven years, that might overwhelm robust protection already inside every appliance. That solution is provided by something completely different.