I doubt it. Like MI-XC mentions you need to decide where your priorities are.
I had a great personal trainer in 2012-2014. I loved squats and deadlifting yet I wanted to be a fast cyclist. He would never (ever) let me go heavy on legs and instead put a lot of emphasis on explosive power (such as jump squats with light weights after starting with no weight and building up). A lot of band work for strengthening stabilizing muscles and dragging weight plates around under my feet while stabilizing my upper body on a medicine ball.
I thought it was kind of crazy because peak deadlift for me was easily over 400 for reps and I thought if I could get back there and ride a lot my sprint would be insane. But doing it my way I never would have been there for the sprint. Yes we did some squats and deads but I don’t think we ever went over 225 and probably did most work well under 150 but for a ton of reps. So I emphasized getting my aerobic strength high, dropped all the heavy lifting at my trainer’s insistence, and ended up setting power PR’s for my sprint pushing over 1400 watts at 170lbs (Cat 5 at the time), over 40 years old too.
You ask, “maybe I’m just not a cyclist?” Are you? You decide what lights your fire and you can get there. 300 watt FTP at your weight is definitely a carrot worth chasing and I think you can get there.
Figure out your lean mass and use this as a guide:
"Athletes often ask me what their FTP should be. That’s hard to answer because (as usual) there are so many “it depends.” But here’s a quick and dirty way to estimate what your FTP based on body weight, age and gender…
Step 1. Double your body weight (lean mass not total weight - my comment) in pounds (1 kg = 2.2 lbs). Example: A body weight of 154 pounds (70 kg) estimates an FTP of 308 watts (154 x 2 = 308).
Step 2. Subtract 0.5% for every year beyond age 35. Example: If the above 154-pound rider is 50 years old he would subtract 7.5% from 308 (50 – 35 = 15 x 0.005 = 0.075). This would predict an FTP of 285 (308 x 0.075 = 23.1, 308 – 23.1 = 284.9).
Step 3. Women riders can subtract 10% from the estimated FTP as found in steps 1 and 2 above. Example: A 120-pound (54.5-kg) woman who is 40 years old would have an estimated FTP of 211 watts (120 x 2 = 240, 240 – 2.5% = 234, 234 – 10% = 210.6)."