That's just marketing.
Zero reason to suffer the terrible dry grip of winter tires if there's no winter precipitation expected. As soon as existing snow melts, and as long as weather is warm enough for new precipitation to melt - no reason not to change.
Finding #1: The main benefit of winter tires is improved tire adhesion, braking and cornering performance–not acceleration performance.
Another common misperception is that winter tires are only useful in snow. Winter tires are also specifically designed to provide improved traction on ice, and somewhat surprisingly, cold roads. The rubber compound used in winter tires is specially formulated to remain pliable in cold conditions, which improves grip. These tires have a low glass-transition temperature with specific tread-block size and thin slits called ‘siping’ to improve traction. Summer and all-season tires have higher glass transition temperatures so they can withstand the high road-surface temperatures experienced during summer. Winter tires should not be used during warmer seasons, as their performance diminishes and they will experience excessive tread wear.
Tires are very complex systems full of compromises that result in a wide range of competing performance characteristics. Several hundred ingredients are used to produce quality tires, and the manufacturing and curing processes are highly complex and controlled to produce desired characteristics. Tires made for warm weather conditions do not perform as well in cold weather, and vice versa. In general, a tire optimized for a specific application will almost certainly be suboptimal in a different application. Winter tires are optimized to operate when road surface temperatures are at or below 7 °C (45 °F), and in general they outperform other tires below this temperature even when ice 3 and snow are not present (TRAC, 2015). Even on dry pavement at temperatures just below freezing, stopping distances for vehicles with winter tires are as much as 30% shorter than for vehicles with all-season tires. Winter tires deliver better traction on an ice- or snow-covered road surface at -30 °C (-22 °F) than all-season tires at 4 °C (39 °F) (TRAC, 2015).
Finding #2: Winter tires provide improved traction on roads that are below 7 °C (45 °F) even when snow and ice are not present.
Comparing tire traction performance by tire type is difficult because the friction coefficient of ice and snow is highly temperature dependent, particularly when near freezing. Based on limited data from a literature review of winter tires conducted by the Traffic Injury Research Foundation (Brown, 2012), it is estimated that the relative stopping-distance performance of winter tires on packed snow is approximately 35% shorter than for all-season tires and about 50% shorter than for summer tires. Substantial improvements in high-speed vehicle cornering performance with winter tires were also reported (Brown, 2012).
Finding #3: Stopping-distance performance of winter tires on packed snow is typically about 35% shorter than all-season tires and 50% shorter than summer tires.
Finding #4: Winter-tire improvements in stopping distance also extend to improvements in cornering capability.
Source: Woodrooffe, J. (2016).
Ten surprising findings about winter tires: It is not just about snow (No. SWT-2016-10). Report No. SWT-2016-10). Ann Arbor: University of Michigan.
I'd rely more on this report than speculations on marketing, especially regarding safety of oneself and others on the road and potentially avoiding any related cost + collateral damage to save a few hundred bucks x few years.
I'd also relate with F1 races where each competitor will choose their own tire specs (soft/medium/hard/extra hard) depending on road surface temperature/weather (rain/wet/hot/etc.) for wear and adhesion. There's obviously some strategy and scientific reason for doing so.
