For a small resort pack (usually 15–20L), skipping compression straps can actually be fine, and it keeps the pack lighter and simpler. If you're just carrying a water bottle, a snack, and an extra layer, the load is small enough that shifting isn't a major issue. You won't be shedding and adding gear throughout the day the way you would on a backcountry tour.
The tradeoff is that the pack's volume is fixed — so if you're only using half the capacity, the pack won't cinch down and may feel a bit floppy or bulky against your back. This can be annoying on chairlifts or when you're making quick turns.
If you prefer a slim, clean pack for short resort days and you pack it full, no compression works well. But if you tend to carry variable loads or want the option to tighten things down, look for at least side compression straps instead.