Here's why:
* It's already a comparative form: The word "inviting" comes from the verb "invite" and is actually the present participle form, which often carries a comparative sense. It implies a higher level of attractiveness or temptation than simply "attractive" or "tempting".
* No clear superlative: There's no natural way to form a superlative for "inviting" in English. You could say something is "most inviting" but it sounds a bit awkward and redundant.
Instead of using comparative and superlative forms, here's how you can convey the meaning of higher degrees of attractiveness or temptation:
* More inviting: This emphasizes the comparative aspect.
* Extremely inviting: This emphasizes a strong level of attraction.
* Irresistibly inviting: This uses a stronger adjective to convey the extreme level of attraction.
For example, instead of "This offer is more inviting than the other one," you might say, "This offer is extremely inviting."