Isn't or IS? LOL

It's not necessarily a great use of MRs. In an absolute vacuum if you had 270,000 MRs...you could cash them out for $3,400 with a Schwab plat. You could get gift cards totaling $2,700. You could potentially get even more value from another redemption method.
OR you could transfer to SPG, then to Marriott and get a nights and flights. The 120k SW points are worth $1,800 let's say. The 7 nights at a Cat 5 (let's assume it's $150 per night) would be $1,050. So you just got $2,850 of value. Barely more than the Gift cards and LESS than the Schwab or other methods.
It's more palateable in a situation where you need to top off your Marriott points balance to hit a nights and flights and you already have a bunch of the points needed.