"Let's hope your dice aren't that much on-fire, then, 'cause I'm fairly certain it'll require a heck of a lot more than 20 shots to take out a Land Raider. If you look at the stats for a larger monstrous creature in AoS, you're looking at 12-16 wounds, often with a 3+/4+ save.
A standard lasgun will likely be a 4+ hit, 4/5+ wound and no save modifier. Assuming 4+ to wound, and the Land Raider has a 3+ save (2+ is exceptionally rare in AoS), 20 shots (I know you said hits, but I'll assume you meant shots) will become 10 hits, 5 wounds, 1-2 failed saves. If you did actually mean hits, instead of shots, then double to 2-4 wounds.
The Land Raider will likely have 16, or more, wounds, so you've barely scratched it. Haven't even done enough damage to reduce it to the next damage category on its chart (usually requires 3 wounds for that)."
... Yes because people only bring 10 lasguns to a fight.... Gentlemen I'm calling it now 8th will be the edition dominated by the basic weapon. Why take specialized lascannons when for the same price you get many more lasguns? the math he's dolling out here is terrifying. if a lasgun only wounded a 6 we'd be talking a different beast all together. but this is GW saying a lasgun will wound a 16 wound landraider on a 4+.... to do the math that's average of 192 shots to kill a land raider assuming BS 3. or roughly 9 squads of unupgraded lasgun soldiers or if you give them two turns about 4-5 squads which is the cost of the land raider, has over 3 times the number of wounds. That's a basic guardsman squad people. 8th edition will be the edition where no one bothers with specialized weapons because the bog standard infantry weapon is far more effective or at least versatile for the points.
That's my opinion YMMV
Edit: also replace lasgun with shoota, termagaunts, ect, concept remains the same. the basic cheap infantry weapon just got a lot more powerful